board/radxa/rock5b: use gpt partition table instead of hybrid

Partition table hybrid means GPT + MBR.
There is no need to keep the MBR when using GPT, so migrate to GPT only.

This change also requires us to migrate from partition-type to
partition-type-uuid, otherwise genimage won't generate an image.

Note that GPT itself always writes a "protective MBR" at LBA 0.

Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

board/radxa/rock5b/genimage.cfg

@@ -2,7 +2,7 @@
 
 image sdcard.img {
 	hdimage {
-		partition-table-type = "hybrid"
+		partition-table-type = "gpt"
 	}
 
 	partition uboot {
@@ -12,7 +12,7 @@ image sdcard.img {
 	}
 
 	partition rootfs {
-		partition-type = 0x83
+		partition-type-uuid = L
 		image = "rootfs.ext2"
 	}
 }