grub.cfg: set serialno for boot_fat.uefi.img

set it to fixed 0123456789 so that we could see the serial number
correctly when we flash with boot_fat.uefi.img for development

Otherwise what we see is something like this:
$ adb devices
List of devices attached
(no serial number)  device

$

Test: adb devices

Change-Id: I2bdb00ddc513f9b64716f823618d38735c7e43d4
Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>
diff --git a/bootloader/EFI/BOOT/grub.cfg b/bootloader/EFI/BOOT/grub.cfg
index 096a147..f8a13a7 100644
--- a/bootloader/EFI/BOOT/grub.cfg
+++ b/bootloader/EFI/BOOT/grub.cfg
@@ -3,35 +3,35 @@
 menuentry 'AOSP' {
     search.fs_label boot root
     set root=($root)
-    linux /kernel console=ttyFIQ0 androidboot.console=ttyFIQ0 androidboot.hardware=hikey firmware_class.path=/system/etc/firmware efi=noruntime printk.devkmsg=on
+    linux /kernel console=ttyFIQ0 androidboot.console=ttyFIQ0 androidboot.hardware=hikey firmware_class.path=/system/etc/firmware efi=noruntime printk.devkmsg=on androidboot.serialno=0123456789
     initrd /ramdisk.img
     devicetree /hi6220-hikey.dtb
 }
 menuentry 'AOSP-DEBUG' {
     search.fs_label boot root
     set root=($root)
-    linux /kernel earlycon=pl011,0xf7113000 no_console_suspend=1 console=ttyFIQ0 androidboot.console=ttyFIQ0 sysrq_always_enabled androidboot.hardware=hikey firmware_class.path=/system/etc/firmware efi=noruntime printk.devkmsg=on
+    linux /kernel earlycon=pl011,0xf7113000 no_console_suspend=1 console=ttyFIQ0 androidboot.console=ttyFIQ0 sysrq_always_enabled androidboot.hardware=hikey firmware_class.path=/system/etc/firmware efi=noruntime printk.devkmsg=on androidboot.serialno=0123456789
     initrd /ramdisk.img
     devicetree /hi6220-hikey.dtb
 }
 menuentry 'AOSP-CONSOLE' {
     search.fs_label boot root
     set root=($root)
-    linux /kernel console=ttyAMA3,115200 androidboot.console=ttyAMA3 fiq_debugger.disable=Y androidboot.hardware=hikey firmware_class.path=/system/etc/firmware efi=noruntime printk.devkmsg=on
+    linux /kernel console=ttyAMA3,115200 androidboot.console=ttyAMA3 fiq_debugger.disable=Y androidboot.hardware=hikey firmware_class.path=/system/etc/firmware efi=noruntime printk.devkmsg=on androidboot.serialno=0123456789
     initrd /ramdisk.img
     devicetree /hi6220-hikey.dtb
 }
 menuentry 'AOSP@720P' {
     search.fs_label boot root
     set root=($root)
-    linux /kernel console=ttyFIQ0 androidboot.console=ttyFIQ0 androidboot.hardware=hikey firmware_class.path=/system/etc/firmware efi=noruntime video=HDMI-A-1:1280x720@60 printk.devkmsg=on
+    linux /kernel console=ttyFIQ0 androidboot.console=ttyFIQ0 androidboot.hardware=hikey firmware_class.path=/system/etc/firmware efi=noruntime video=HDMI-A-1:1280x720@60 printk.devkmsg=on androidboot.serialno=0123456789
     initrd /ramdisk.img
     devicetree /hi6220-hikey.dtb
 }
 menuentry 'AOSP@SVGA' {
     search.fs_label boot root
     set root=($root)
-    linux /kernel console=ttyFIQ0 androidboot.console=ttyFIQ0 androidboot.hardware=hikey firmware_class.path=/system/etc/firmware efi=noruntime video=HDMI-A-1:800x600@60 printk.devkmsg=on
+    linux /kernel console=ttyFIQ0 androidboot.console=ttyFIQ0 androidboot.hardware=hikey firmware_class.path=/system/etc/firmware efi=noruntime video=HDMI-A-1:800x600@60 printk.devkmsg=on androidboot.serialno=0123456789
     initrd /ramdisk.img
     devicetree /hi6220-hikey.dtb
 }