usb: gadget: tcm: factor out f_tcm

Prepare for converting tcm to new function registration interface.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/usb/gadget/function/tcm.h

@@ -129,4 +129,4 @@ struct f_uas {
 
 extern struct usbg_tpg *the_only_tpg_I_currently_have;
 
-#endif
+#endif /* __TARGET_USB_GADGET_H__ */