mm-video-v4l2: venc: Remove level calculation in OMX

Firmware does level calculation for encoder and we want the
level to be set by firmware. We achieve this by setting
default level as unknown unless specified by the client.

CRs-Fixed: 2016785
Change-Id: Ib5c7c1d75e308c698f91ad945d87ae3b5d50c152
3 files changed