msm: camera: isp: Provision to read svs freq for VFE

This change gives way to read svs freq for certain targets
for which VFE's have svs freq defined.

Change-Id: I749327861e4392c6f3f24235c1e9b47b684f1362
Signed-off-by: Rajeev Kulkarni <krajeev@codeaurora.org>