Input: elan_i2c - clear INT before resetting controller

Input: elan_i2c - clear INT before resetting controller

[ Upstream commit 4b3c7dbbfff0673e8a89575414b864d8b001d3bb ]

Some old touchpad FWs need to have interrupt cleared before issuing reset
command after updating firmware. We clear interrupt by attempting to read
full report from the controller, and discarding any data read.

Signed-off-by: KT Liao <kt.liao@emc.com.tw>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>