Input: tca8418 - remove set but not used variable 'max_keys'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/input/keyboard/tca8418_keypad.c: In function tca8418_keypad_probe:
drivers/input/keyboard/tca8418_keypad.c:269:24: warning: variable max_keys set but not used [-Wunused-but-set-variable]

It's not used since commit 16ff7cb1848a ("Input:
tca8418-keypad - switch to using managed resources")

Signed-off-by: YueHaibing <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/keyboard/tca8418_keypad.c

···
 	struct tca8418_keypad *keypad_data;
 	struct input_dev *input;
 	u32 rows = 0, cols = 0;
-	int error, row_shift, max_keys;
+	int error, row_shift;
 	u8 reg;
 
 	/* Check i2c driver capabilities */
···
 	}
 
 	row_shift = get_count_order(cols);
-	max_keys = rows << row_shift;
 
 	/* Allocate memory for keypad_data and input device */
 	keypad_data = devm_kzalloc(dev, sizeof(*keypad_data), GFP_KERNEL);