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>

SVN-Revision: 38116

target/linux/ar71xx/image/Makefile

@@ -14,7 +14,7 @@ $(BIN_DIR)/$(IMG_PREFIX)-$(2)-$(patsubst jffs2-%,jffs2,$(patsubst squashfs-%,squ
 endef
 
 define rootfs_align
-$(patsubst %-256k,0x40000,$(patsubst %-128k,0x20000,$(patsubst %-64k,0x10000,$(patsubst squashfs-%,0x4,$(1)))))
+$(patsubst %-256k,0x40000,$(patsubst %-128k,0x20000,$(patsubst %-64k,0x10000,$(patsubst squashfs%,0x4,$(patsubst root.%,%,$(1))))))
 endef
 
 define sysupname