msm: camera: Add proper error handling during msm_open

Currently VFE and VPE are singleton. Hence only one camera
instance can use the ISP modules. Added check for the same.
Also added proper error handling to reset the reference count
and free the pcam instance incase of failure

CRs-Fixed: 340315
Change-Id: Ia12a3f305aa03eb70b9ce8b5ed526f1d5e4e7568
Signed-off-by: Sunid Wilson <sunidw@codeaurora.org>