vp9_ethread: change mask_filter to a local variable

The mask_filter in RD_OPT struct is used to record rd result in
filter decision. It is only used in pick_inter_mode functions,
and is removed from the struct and declared as a local variable.

Change-Id: I3c95c8632ba7241591ce00ef2ef5677b5e297d7b
2 files changed