adm5120: mark the rb1xx subtarget as broken

Signed-off-by: Felix Fietkau <[email protected]>

target/linux/adm5120/rb1xx/target.mk

@@ -1,7 +1,7 @@
 ARCH:=mipsel
 SUBTARGET:=rb1xx
 BOARDNAME:=MikroTik RB-1xx boards
-FEATURES+=tgz
+FEATURES+=tgz broken
 
 define Target/Description
 	Build firmware images for Mikrotik RB-1xx series.