msm: isp: use proper spin lock on isr and tasklet

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 preempt and acuire the lock hold by user,
which will possibly hang CPU.

Avoid the issue to use spin lock irq save consistantly.

Change-Id: I52e17d189668166ae126dc5948fe51bd79ae9859
Signed-off-by: Peter Liu <pingchie@codeaurora.org>
Signed-off-by: Jing Zhou <jzhou70@codeaurora.org>