db845c: Enable earlycon on bootargs

While earlycon doesn't help when the serial driver is a module,
enable earlycon in the boot arguments so we can be able to
debug some of the issues folks are seeing with boots failing.

Change-Id: Ib46b12e2f6c5c44092935742837253128559890a
Signed-off-by: John Stultz <john.stultz@linaro.org>
diff --git a/db845c/BoardConfig.mk b/db845c/BoardConfig.mk
index 0af0aaf..3c925b3 100644
--- a/db845c/BoardConfig.mk
+++ b/db845c/BoardConfig.mk
@@ -10,7 +10,7 @@
 BOARD_MKBOOTIMG_ARGS := --header_version $(BOARD_BOOT_HEADER_VERSION)
 BOARD_KERNEL_BASE := 0x80000000
 BOARD_KERNEL_PAGESIZE := 2048
-BOARD_KERNEL_CMDLINE := firmware_class.path=/vendor/firmware/ androidboot.hardware=db845c
+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
 
 # Image Configuration