msm: camera: don't cut to 8bits for validating enum variable

In msm_ispif_is_intf_valid(),
we convert a enum variable msm_ispif_vfe_intf,
to uint8_t type for validating.

This could cause potential issue,
if the value is crafted in such a way that lower 8bits pass the validation.

Don't use uint8_t as input parm to avoid such vulnerability.

CRs-Fixed: 2008469
Change-Id: I4ee400ac0edd830decfbe5712966d968976a268a
Signed-off-by: Gaoxiang Chen <gaochen@codeaurora.org>