msm: camera: isp: Limit sof_in_epoch log to first frame

This change limits SOF in early PCR log to the first
frame for that context. This log is needed to catch
unexpected reg updates on first frame after stream on.

CRs-Fixed: 2553728
Change-Id: Icad85aeab2b095a6b95889c933a2de34acebed80
Signed-off-by: Venkat Chinta <vchinta@codeaurora.org>
Signed-off-by: Vishalsingh Hajeri <vhajeri@codeaurora.org>
Signed-off-by: Pavan Kumar Chilamkurthi <pchilamk@codeaurora.org>