Set the base_mv_aggressive for temporal enhancement layers (TL > 0).
Under the aggressive mode, skip the NEWMV depending on the
SSE of the base_mv. Also reduce the subpel motion to 1/2 under
aggressive mode if base_mv is good.

Speedup ~3% with small/negligible loss in quality on RTC.
Affects speed >= 6.

Change-Id: I89341b279cad6da2a04b76d5e726016191dacdb8