msm: camera: isp: Fix TPG acquire error

There was an incorrect check causing a TPG resource failing to
acquire. This change will resolve that issue.

Change-Id: Ibe332926a826324bd7a613f0c12dbfae04d53676
Signed-off-by: Harsh Shah <harshs@codeaurora.org>
Signed-off-by: Vishalsingh Hajeri <vhajeri@codeaurora.org>