For SVC 1 pass non-rd pickmode, the interpolation filter for the
upsampling of the golden (spatial) reference was not being explicitly
set and instead was takin gwhatever value was set in the previous
mode/block (which would be either EIGHTTAP or EIGHTAP_SMOOTH).

Fix it to the default EIGHTTAP for now, to be updated/selected
adaptively in a later change.

Minor adjustmemt to rate targeting thresholds in datarate unittests.

Change-Id: I52085048674072c6cfb7163e11e9a2658d773826