Input: mpr121 - handle multiple bits change of status register

commit 08fea55e upstream.

This driver reports input events on their interrupts which are triggered
by the sensor's status register changes.  But only single bit change is
reported in the interrupt handler.  So if there are multiple bits are
changed at almost the same time, other press or release events are ignored.

This fixes it by detecting all changed bits in the status register.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Oliver Neukum <ONeukum@suse.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>