DO NOT MERGE mm-video-v4l2: vdec: deprecate unused config OMX_IndexVendorVideoExtraData

This config (used to set header offline) is no longer used. Remove handling
this config since it uses non-process-safe ways to pass memory pointers.

Fixes: Security Vulnerability - Segfault in MediaServer (libOmxVdec problem #2)
Bug: 27475409

Change-Id: I7a535a3da485cbe83cf4605a05f9faf70dcca42f
