Removed MV costing from ARNR filtering

The ARNR filter uses a motion compensated temporal filter,
but the motion estimation implementation accounts for the
cost of the mv in its decision making process. The ARNR
filter uses a dummy cost table initialized to 0 as a way
to ignore the mv costs (which are irrelevant to the filter).

This CL modifies the ARNR filter implementation to so that
the mv costing is ignored without the requirement for
dummy tables.

Change-Id: I0dd9620c3b70682f938b2a70912c11d4d7c9284c