staging: wlan-ng: Remove unused function hfa384x_docmd_async()

Remove unused function hfa384x_docmd_async.
Issue found with Coccinelle.
Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190712062807.9361-7-nishkadg.linux@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wlan-ng/hfa384x_usb.c

@@ -826,14 +826,6 @@ static inline int hfa384x_docmd_wait(struct hfa384x *hw,
 	return hfa384x_docmd(hw, DOWAIT, cmd, NULL, NULL, NULL);
 }
 
-static inline int
-hfa384x_docmd_async(struct hfa384x *hw,
-		    struct hfa384x_metacmd *cmd,
-		    ctlx_cmdcb_t cmdcb, ctlx_usercb_t usercb, void *usercb_data)
-{
-	return hfa384x_docmd(hw, DOASYNC, cmd, cmdcb, usercb, usercb_data);
-}
-
 static inline int
 hfa384x_dormem_wait(struct hfa384x *hw,
 		    u16 page, u16 offset, void *data, unsigned int len)