input: atmel_mxt_ts: amend finger status check

Touch screen driver checks finger status when releasing unwanted touch
events. Current status check does not cover an unwanted finger status.
This introduces extraneous events when device goes to suspend.

CRs-Fixed: 595019
Change-Id: I3c230cb98d5866edf2bc2f433765f787e518ac93
Signed-off-by: Chun Zhang <chunz@codeaurora.org>