ar71xx: image: improve the CatFiles macro

Make it possible to append the rootfs image directly
to the kernel.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@38115 3c298f89-4303-0410-b956-a3cf2f4a3e73
ar71xx: image: improve the rootfs_align macro

Improve the macro to return correct value for
all squashfs variant.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@38116 3c298f89-4303-0410-b956-a3cf2f4a3e73
ar71xx: image: add mtdpartsize macro

The new macro will be used to determine the firmware
partition size from an MTD layout.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@38117 3c298f89-4303-0410-b956-a3cf2f4a3e73