Input: matrix_keypad - use request_any_context_irq()

When trying to use the matrix-keypad driver with GPIO drivers that
require nested irq handlers (e.g. I2C GPIO adapters like PCA9554),
request_irq() fails because the GPIO driver requires a threaded
interrupt handler.

Use request_any_context_irq() to be able to use any GPIO driver as
keypad driver.

Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>