msm: isp: camera_v2: use vfe0 when dual_isp_sync enabled

when dual vfe sync is enabled vfe0 struct is used access
common variable, if disabled use vfe1.

Change-Id: Ib418cfe8c4ceec8c204f36482402e0746dc5755b
Signed-off-by: Srikanth Uyyala <suyyala@codeaurora.org>