input: atmel_mxt_ts: Do not disable multi-touch object in suspend

Disabling multi-touch object when touch is operational
may result in improper state of the controller causing it to
report invalid number of touches.

There is no negative impact on power or operation of the
controller after this change.

CRs-Fixed: 351462
Change-Id: I170c094386be415dbc53e15e6e36e2d8de832c5d
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>