msm: camera: isp: fix pingpong status race condition

Frame request from userspace can happen at any moment relative to
frame. However usage of ping pong flag in this routine is considered
as if it is called between SOF and AXI IRQs. If frame request arrives
later, address is configured incorrectly. This change uses ping pong
taken during AXI irq - which is synchronous with change of ping pong
flag and uses it for next SOF to SOF interval, avoiding race
condition.

Change-Id: I6c99632e38214ee568d15aaa78e67a51ebac97df
Signed-off-by: Petar Sivenov <psiven@codeaurora.org>