msm: vidc: Modify step and menu mask of custom controls

As per V4L2, Step should be 0 for Menu controls and menu_mask
should be 0 for other controls.

CRs-Fixed: 2384822
Change-Id: I5342a8f57f1bd837a0753b6ad3bbb8f2339166c2
Signed-off-by: Chinmay Sawarkar <chinmays@codeaurora.org>