msm: venc: Disable input extradata plane for secure encoding

For secure encoding case, there is no camera usage. Hence,
by default make number of planes as 1. If any input requires
extradata, client will enable it and driver will update
number of planes.

Change-Id: Id9afd0a286a53d5d4c6045ba58227f57a0a8e0ca
Signed-off-by: Darshana Patil <darshana@codeaurora.org>