Removed firstpass motion map

Removed firstpass motion map

The firstpass motion map consists of an 8-bit flag for
each MB indicating how strongly the firstpass code
believes it should be filtered during the second pass
ARNR filtering.

For long or large format material the motion map can
become extremely large and hamper the operation of
the encoding process.

This change removes the motion map altogether, leaving
the second pass to rely on the magnitude of the motion
compensated error to determine the filter weight to
use for the MB during ARNR filtering.

Tests on the derf set indicate that the effect of this
change is neutral, with some small wins and losses. The
motion map has therefore been removed based on
a cost/benefit evaluation.

Change-Id: I53e07d236f5ce09a6f0c54e7c4ffbb490fb870f6