msm: vidc: Set default values for plane and image sizes

G_FMT shall return a valid non-zero value to client.
plane_sizes are set in REQBUFS but G_FMT is not necesary
call after REQBUFS.

Change-Id: I72e356d44161ba30019ecb029f1bb2da3d2267b1
Signed-off-by: Jorge Solano Altamirano <jsolano@codeaurora.org>