scripts: gen_image_generic: allow the partition types to be set

The use case for this is to set the kernel partition as the
EFI system partition. Versions of U-Boot with the
EFI boot manager (eficonfig and efidebug commands) will
store their boot order data on the ESP.

Signed-off-by: Mathew McBride <matt@traverse.com.au>
(cherry picked from commit 701d774f54)

scripts/gen_image_generic.sh

@@ -9,8 +9,10 @@ fi
 OUTPUT="$1"
 KERNELSIZE="$2"
 KERNELDIR="$3"
+KERNELPARTTYPE=${KERNELPARTTYPE:-83}
 ROOTFSSIZE="$4"
 ROOTFSIMAGE="$5"
+ROOTFSPARTTYPE=${ROOTFSPARTTYPE:-83}
 ALIGN="$6"
 
 rm -f "$OUTPUT"
@@ -19,7 +21,7 @@ head=16
 sect=63
 
 # create partition table
-set $(ptgen -o "$OUTPUT" -h $head -s $sect ${GUID:+-g} -p "${KERNELSIZE}m${PARTOFFSET:+@$PARTOFFSET}" -p "${ROOTFSSIZE}m" ${ALIGN:+-l $ALIGN} ${SIGNATURE:+-S 0x$SIGNATURE} ${GUID:+-G $GUID})
+set $(ptgen -o "$OUTPUT" -h $head -s $sect ${GUID:+-g} -t "${KERNELPARTTYPE}" -p "${KERNELSIZE}m${PARTOFFSET:+@$PARTOFFSET}" -t "${ROOTFSPARTTYPE}" -p "${ROOTFSSIZE}m" ${ALIGN:+-l $ALIGN} ${SIGNATURE:+-S 0x$SIGNATURE} ${GUID:+-G $GUID})
 
 KERNELOFFSET="$(($1 / 512))"
 KERNELSIZE="$2"