Input: matrix_keypad - remove an unused field in struct matrix_keypad

In "struct matrix_keypad", the 'gpio_all_disabled' field is unused.
Remove it.

Found with cppcheck, unusedStructMember.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/4f1a946789445500b6118b9ee1d6ef5255f8c696.1714542052.git.christophe.jaillet@wanadoo.frSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/matrix_keypad.c

@@ -37,7 +37,6 @@ struct matrix_keypad {
 	spinlock_t lock;
 	bool scan_pending;
 	bool stopped;
-	bool gpio_all_disabled;
 };
 
 /*