msm: camera2: cpp: Lock cpp timer operations

CPP timer is used to notify process frame timeout. It is not
protected by any lock machanism and certain false operations
can occur. Spin lock is added to avoid undesired sequences
of timer modifications.

Change-Id: I91d8aa7e2cd94d329ff209259fc7a41575282457
Signed-off-by: Iliya Varadzhakov <ivarad@codeaurora.org>
Signed-off-by: Rajakumar Govindaram <rajakuma@codeaurora.org>