Move protocol makefiles into their respective folders (#21332)

* Move protocol makefiles into their respective folders

* Fix USB-USB converter

builddefs/build_keyboard.mk

@@ -440,10 +440,11 @@ include $(PLATFORM_PATH)/$(PLATFORM_KEY)/platform.mk
 -include $(PLATFORM_PATH)/$(PLATFORM_KEY)/flash.mk
 
 ifneq ($(strip $(PROTOCOL)),)
-    include $(TMK_PATH)/protocol/$(strip $(shell echo $(PROTOCOL) | tr '[:upper:]' '[:lower:]')).mk
+PROTOCOL_KEY = $(strip $(shell echo $(PROTOCOL) | tr '[:upper:]' '[:lower:]'))
 else
-    include $(TMK_PATH)/protocol/$(PLATFORM_KEY).mk
+PROTOCOL_KEY = $(PLATFORM_KEY)
 endif
+include $(TMK_PATH)/protocol/$(PROTOCOL_KEY)/$(PROTOCOL_KEY).mk
 
 # Setup definitions based on the selected MCU
 $(eval $(call add_qmk_prefix_defs,MCU_ORIG,MCU))

tmk_core/protocol.mk

@@ -99,7 +99,7 @@ ifeq ($(strip $(SHARED_EP_ENABLE)), yes)
 endif
 
 ifeq ($(strip $(USB_HID_ENABLE)), yes)
-    include $(TMK_DIR)/protocol/usb_hid.mk
+    include $(TMK_DIR)/protocol/usb_hid/usb_hid.mk
 endif
 
 # Search Path