adjust sad per bit constants

While investigating the effect of DC values on SAD and SSE in motion
estimation, a side finding indicates the two table of constants need
be adjusted. The adjustment was done by multiplying old constants by
90% with rounding. Also absorb the 1/2 scaling constant into the two
tables. Refer to change Ifa285c3e for background of the 1/2 factor.

Cif set test showed a very small gain on all metric.

Change-Id: I04333527a823371175dd46cb04a817e5b9a8b752