msm: camera: isp: Add enable/disable IRQ functions to Controller

Add APIs to enable and disable irq events while still subscribed
for the IRQ bits in IRQ controller. This enables the driver to temporary
ignore the IRQs while still keeping the event handler in place. This is
needed when an error occurs and we are trying to recover. After the
error there can be an IRQ storm and we need to disable the IRQ,
then reset the HW and restart the HW after enabling the IRQ again. Since
this disabling of IRQ to avoid IRQ storm needs to happen in top half, we
cannot call unsubscribe which would free the event handler that contains
the top half handling function being executed.

Change-Id: Ic498cf0703db85ae41690374e27e22b1fbd30f2e
Signed-off-by: Alok Pandey <akumarpa@codeaurora.org>
Signed-off-by: Harsh Shah <harshs@codeaurora.org>