The function scale_sse_threshold() returns a threshold scaled
if necessary for use with 10 and 12 bit from an 8 bit baseline.

SSE error values would be expected to rise for the 10 and 12
bit cases where there are more bits of precision.

Hence the threshold used for the test should also be scaled up.

Change-Id: I4009c98b6eecd1bf64c3c38aaa56598e0136b03d