msm: keypad: fix half level voltage after keyscan on 8905

During VT call mute key was not working because of half
level voltage due to low pull down. This fix issue by
pulling row to low and making making as input again.

Change-Id: I65187d72faa02e934a88e2f23db46f2ee67cca56
Signed-off-by: Chetan C R <cravin@codeaurora.org>