kernel/rotary-gpio-custom: drop Build/Prepare rule in favor of default one

Signed-off-by: Alexandru Ardelean <[email protected]>

package/kernel/rotary-gpio-custom/Makefile

@@ -39,11 +39,6 @@ MAKE_OPTS:= \
 	EXTRA_CFLAGS="$(EXTRA_CFLAGS)" \
 	$(EXTRA_KCONFIG)
 
-define Build/Prepare
-	mkdir -p $(PKG_BUILD_DIR)
-	$(CP) ./src/* $(PKG_BUILD_DIR)/
-endef
-
 define Build/Compile
 	$(MAKE) -C "$(LINUX_DIR)" \
 		$(MAKE_OPTS) \