msm: camera: isp: Turn off irq and overflow signal

When vfe is halted, an overflow signal could be generated that
has side effects. Turn off this signal when halting vfe. Also,
disable interrupts when halting the vfe due prevent other side
effects.

CRs-Fixed: 953865
Change-Id: I706d796c500db4a201149196d7ed15965c0b1bb7
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>