uboot-envtools: oxnas: sync with current oxnas/ox820 DTS

Use tested values on shuttle,kd20 and assumed values for
mitrastar,stg-212 and cloudengines,pogoplug*.
akitio users have yet to report back stock flash layout to support
vendor bootloader environment there as well.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

package/boot/uboot-envtools/files/oxnas

@@ -13,11 +13,10 @@ touch /etc/config/ubootenv
 board=$(board_name)
 
 case "$board" in
-akitio|\
-kd20|\
-stg212)
-	ubootenv_add_uci_config "/dev/ubi0_0" "0x0" "0x4000" "0x1F000" "1"
-	ubootenv_add_uci_config "/dev/ubi0_1" "0x0" "0x4000" "0x1F000" "1"
+"cloudengines,pogoplug"* | \
+"mitrastar,stg-212" | \
+"shuttle,kd20")
+	ubootenv_add_uci_config "/dev/mtd2" "0x0" "0x2000" "0x2000" "1"
 	;;
 esac