msm: camera: ispif: Validate VFE num input during reset

Userspace supplies the actual number of used VFEs in session to ISPIF.
Validate the userspace input value and if found to be invalid, return
error.

CRs-Fixed: 898074
Signed-off-by: Venu Yeshala <vyeshala@codeaurora.org>
Signed-off-by: Suman <Mukherjee&lt;sumam@codeaurora.org>
Change-Id: I3288ddb6404e817a705a92281b4c54666f372c56