Input: stmpe-keypad - fix valid key line bitmask

The bitmask comment says it will enable GPIO 8-14 and 16-20 for keypad use,
but it actually enables GPIO 8-11 and 13-20 due to a bit error.

Instead of masking of the "hole" at GPIO 12 (which is used for keypad
output 4) mask of the proper "hole" at GPIO 15.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/stmpe-keypad.c

@@ -86,7 +86,7 @@ static const struct stmpe_keypad_variant stmpe_keypad_variants[] = {
 		.max_cols		= 8,
 		.max_rows		= 12,
 		.col_gpios		= 0x0000ff,	/* GPIO 0 - 7*/
-		.row_gpios		= 0x1fef00,	/* GPIO 8-14, 16-20 */
+		.row_gpios		= 0x1f7f00,	/* GPIO 8-14, 16-20 */
 	},
 	[STMPE2403] = {
 		.auto_increment		= true,