Remove default folders for the Planck & Preonic (#3497)

* remove planck default folder

* Update rules.mk

keyboards/planck/rules.mk

@@ -44,5 +44,3 @@ SLEEP_LED_ENABLE = no    # Breathing sleep LED during USB suspend
 
 LAYOUTS = ortho_4x12 planck_mit planck_grid
 LAYOUTS_HAS_RGB = no
-
-DEFAULT_FOLDER = planck/rev5

keyboards/preonic/rules.mk

@@ -72,5 +72,3 @@ API_SYSEX_ENABLE = no
 SLEEP_LED_ENABLE = no    # Breathing sleep LED during USB suspend
 
 LAYOUTS = ortho_5x12
-
-DEFAULT_FOLDER = preonic/rev2