msm: camera: isp: avoid spin lock recursion on same CPU

When CPU do spin lock irq save, it will disable irq/preemption.
If the same CPU do spin lock without disabling irq,
then irq context can trigger spin lock irq save
which will hang CPU since the irq/preemption is disabled.

Avoid the issue to use spin lock irq save consistantly.

Change-Id: I38bf80be58744dabf7c2554b50b686b1e304fc4c
Signed-off-by: Peter Liu <pingchie@codeaurora.org>