Remove makefile from Let's Split piemod.

keyboards/lets_split/keymaps/piemod/Makefile

@@ -1,10 +0,0 @@
-SUBPROJECT_DEFAULT = rev4
-
-MOUSEKEY_ENABLE = yes
-BLUETOOTH_ENABLE = yes
-EXTRAKEY_ENABLE = yes
-AUDIO_ENABLE = yes 
-
-ifndef QUANTUM_DIR
-	include ../../../../Makefile
-endif