K3: Make FAT filesystem fill whole partition (#5543)

The default will align the data structures with the cluster size,
which causes the size to not be set to the full partition size. This
causes issues with some board ROMs. Use the -a flag to ignore the
alignment and fill the available space.

Co-authored-by: Igor <igor@armbian.com>

config/sources/families/k3.conf

@@ -64,6 +64,11 @@ function uboot_custom_postprocess() {
 	cp ${SRC}/cache/sources/ti-u-boot/${TIBOOT3_FILE} tiboot3.bin
 }
 
+function pre_prepare_partitions() {
+	# Filesystem must fill partition regardless of alignment
+	mkopts[fat]='-a'
+}
+
 function post_create_partitions() {
 	display_alert "Setting boot partition flags on" "${SDCARD}.raw" "debug"