db845c/BoardConfig.mk: fix the value of androidboot.boot_devices

which should be soc@0/1d84000.ufshc,
as the soc item defined in the dts is "soc: soc@0" like here:
   https://android.googlesource.com/kernel/common/+/refs/heads/android-mainline/arch/arm64/boot/dts/qcom/sdm845.dtsi#705
otherwise links like /dev/block/by-name/super won't be created during the boot,
and will get problem like this:

    [    8.807222] init: Loaded kernel module /lib/modules/xhci-plat-hcd.ko
    [    8.814077] init: [libfs_mgr]ReadFstabFromDt(): failed to read fstab from dt
    [    8.821719] init: Using Android DT directory /proc/device-tree/firmware/android/
    [    8.852403] init: realpath failed: /dev/block/by-name/super: No such file or directory
    [    8.860633] init: Failed to mount required partitions early ...
    [    8.867386] init: InitFatalReboot: signal 6

and vts test failures for following test cases:
    VtsKernelLiblpTest#DeviceTest.BlockDeviceInfo
    VtsKernelLiblpTest#DeviceTest.ReadSuperPartitionCurrentSlot
    VtsKernelLiblpTest#DeviceTest.ReadSuperPartitionOtherSlot

Test: checked that /dev/block/by-name/super is there,
      and the failures of VtsKernelLiblpTest#DeviceTest passed

Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>
Change-Id: I33e3a4dbd7c0435d561f694dc3103736382791e0
diff --git a/db845c/BoardConfig.mk b/db845c/BoardConfig.mk
index 0a30c88..47602f6 100644
--- a/db845c/BoardConfig.mk
+++ b/db845c/BoardConfig.mk
@@ -11,7 +11,7 @@
 BOARD_KERNEL_BASE := 0x80000000
 BOARD_KERNEL_PAGESIZE := 2048
 BOARD_KERNEL_CMDLINE := earlycon firmware_class.path=/vendor/firmware/ androidboot.hardware=db845c
-BOARD_KERNEL_CMDLINE += init=/init androidboot.boot_devices=soc/1d84000.ufshc printk.devkmsg=on
+BOARD_KERNEL_CMDLINE += init=/init androidboot.boot_devices=soc@0/1d84000.ufshc printk.devkmsg=on
 
 # Image Configuration
 BOARD_BOOTIMAGE_PARTITION_SIZE := 67108864 #64M