msm: isp: Add pingpong status to tasklet command

We read pingpong status while handling axi and stats irqs
in tasklet. Due to scheduling delays in tasklet pingpong status is
changing by the time we read. So, read ping pong status in ISR
and forward it to tasklet.

Change-Id: Ib83929cb8e15c28e34ee06275a87b5d6fbfd00e6
Signed-off-by: Srikanth Uyyala <suyyala@codeaurora.org>