ar71xx: disable ap91-5g due to kernel size

This target causes a build failure as the kernel image does not fit
into the kernel partition.

As the kernel is located behind the rootfs, it cannot be enlarged
as the boot entry location would get altered.

Disable this target for now.

Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

target/linux/ar71xx/image/generic.mk

@@ -148,7 +148,6 @@ define Device/ap91-5g
   IMAGE/sysupgrade.bin := append-rootfs | pad-rootfs |\
 	pad-to $$$$(ROOTFS_SIZE) | append-kernel | check-size $$$$(IMAGE_SIZE)
 endef
-TARGET_DEVICES += ap91-5g
 
 define Device/arduino-yun
   DEVICE_TITLE := Arduino Yun