Camera: Update 'indexOfKey' return check

Method 'indexOfKey' will return 'NAME_NOT_FOUND' error
status in case it doesn't find any values matching the
given key. Checking for anything other than this error
code could lead to instabilities.

Bug: 35925482
Test: Manual using application
Change-Id: Ie72eb29776b27a6d485f6e42ee7e62c62795ca9e
(cherry picked from commit 4219c290)