bmips: remove source-only flag

bmips target is now more stable and it's time to start generating buildbot
images in order to receive a wider testing, which will be essential to replace
bcm63xx target in the future.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

target/linux/bmips/Makefile

@@ -7,7 +7,7 @@ CPU_TYPE:=mips32
 BOARD:=bmips
 BOARDNAME:=Broadcom BMIPS
 SUBTARGETS:=bcm6318 bcm6328 bcm6358 bcm6362 bcm6368 bcm63268
-FEATURES:=gpio source-only squashfs usb
+FEATURES:=gpio squashfs usb
 
 KERNEL_PATCHVER:=5.15