Remove lfkeyboards parent rules.mk as its only required for mini1800

keyboards/lfkeyboards/mini1800/rules.mk

@@ -52,6 +52,8 @@ F_USB = $(F_CPU)
 # Interrupt driven control endpoint task(+60)
 OPT_DEFS += -DINTERRUPT_CONTROL_ENDPOINT
 
+# Extra source files for IS3731 lighting
+SRC = TWIlib.c issi.c lighting.c
 
 ifeq ($(strip $(ISSI_ENABLE)), yes)
     # TMK_COMMON_DEFS += -DISSI_ENABLE

keyboards/lfkeyboards/rules.mk

@@ -1 +0,0 @@
-SRC = TWIlib.c issi.c lighting.c