HID: sony: Fix unused function warning

Compiling this driver without setting "CONFIG_SONY_FF" generates the
following warning:

	drivers/hid/hid-sony.c:2358:20: warning: unused function
	'sony_send_output_report' [-Wunused-function]
	static inline void sony_send_output_report(struct sony_sc *sc)
	                   ^
	1 warning generated.

Add the missing preprocessor check to fix it.
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-sony.c

@@ -2355,11 +2355,13 @@ static void motion_send_output_report(struct sony_sc *sc)
 	hid_hw_output_report(hdev, (u8 *)report, MOTION_REPORT_0x02_SIZE);
 }
 
+#ifdef CONFIG_SONY_FF
 static inline void sony_send_output_report(struct sony_sc *sc)
 {
 	if (sc->send_output_report)
 		sc->send_output_report(sc);
 }
+#endif
 
 static void sony_state_worker(struct work_struct *work)
 {