Input: omap4-keypad - use guard notation when acquiring mutex

This makes the code more compact and error handling more robust
by ensuring that mutexes are released in all code paths when control
leaves critical section.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/keyboard/omap4-keypad.c

···
 {
 	u64 changed;
 
-	mutex_lock(&keypad_data->lock);
+	guard(mutex)(&keypad_data->lock);
 
 	changed = keys ^ keypad_data->keys;
 
···
 	omap4_keypad_report_keys(keypad_data, changed & keys, true);
 
 	keypad_data->keys = keys;
-
-	mutex_unlock(&keypad_data->lock);
 }
 
 /* Interrupt handlers */