use preprocessor conditional on backlight initialization

keyboard/planck/Makefile

@@ -126,7 +126,6 @@ COMMAND_ENABLE = yes    # Commands for debug and configuration
 # NKRO_ENABLE = yes		# USB Nkey Rollover - not yet supported in LUFA
 BACKLIGHT_ENABLE = yes  # Enable keyboard backlight functionality
 MIDI_ENABLE = YES 		# MIDI controls
-BACKLIGHT_ENABLE = yes
 
 ifdef MIDI_ENABLE
 	SRC += keymap_midi.c

keyboard/planck/matrix.c

@@ -65,7 +65,9 @@ void matrix_init(void)
     MCUCR |= (1<<JTD);
     MCUCR |= (1<<JTD);
 
+    #if BACKLIGHT_ENABLE == 'yes'
     backlight_init_ports();
+    #endif
 
     // Turn status LED on
     DDRE |= (1<<6);