Make lpf_sb compatible with loopfilter_level, when USE_GUESS_LEVEL = 1.

Filter levels will be selected based on q index and applied for
filtering on Y, U, V planes separately.

Current model only allows to guess one filter level.
Now Y_vert = Y_horz = U = V. In the future, we need to retrain the
model and get filter levels for Y_vert, Y_horz, U and V separately.

When USE_GUESS_LEVEL = 0, lpf_sb can't work with loopfilter_level yet.

Change-Id: Icd774a147c07a4035cf8204a8754b2a99668bbfd