Change mmcboot command for home partition

- Define boot_partition instead of rootfs_partition, this is
significantly less likely to change than rootfs_partition (boot script
uses this).
- Give the kernel the rootfs by PARTUUID, which won't change.

Change-Id: I50c4bde415290c8caf2aa041a48e024392d6b927
diff --git a/include/configs/mt8516-coral.h b/include/configs/mt8516-coral.h
index e7b5e31..f9a981c 100644
--- a/include/configs/mt8516-coral.h
+++ b/include/configs/mt8516-coral.h
@@ -71,10 +71,10 @@
 #else
 #define MMCBOOT \
 	"mmcdev=0\0" \
-	"rootfs_partition=3\0" \
+	"boot_partition=2\0" \
 	"mmcboot=" \
 		"mmc dev ${mmcdev};" \
-		"setenv bootargs ${bootargs} root=/dev/mmcblk${mmcdev}p${rootfs_partition} rootwait; " \
+		"setenv bootargs ${bootargs} root=PARTUUID=02f36a4f-4562-46b2-bbec-bfc1682f9e92 rootwait; " \
 		"ext2load mmc ${mmcdev}:2 " __stringify(CONFIG_SYS_TEXT_BASE) " boot.scr;" \
 		"source; \0"
 #endif /* CONFIG_MTK_ANDROID */