msm: camera: tfe: Dont consider vbi for epoch configuration in case of tpg

In case of TPG enabled, vbi value should be not be
consider in calculating epoch configuration because
vbi value passed is in cycles not in terms of lines
when TPG is selected.

CRs-Fixed: 2797039
Change-Id: Ia8870a8c2516fc2e0b3347ccb6b69db3774e33c1
Signed-off-by: Shravya Samala <shravyas@codeaurora.org>