rtc-svc: Fix to make SVC work for Profile 1

rtc-svc: Fix to make SVC work for Profile 1

Added datarate unittest for 4:4:4 and 4:2:2 input,
for spatial and temporal layers.

Fix is needed in vp9_set_literal_size():
the sampling_x/y should be passed into update_inital_width(),
othewise sampling_x/y = 1/1 (4:2:0) was forced.
vp9_set_literal_size() is only called by the svc and
on dynamic resize.

Fix issue with the normative optimized scaler:
UV width/height was assumed to be 1/2 of Y, for
the ssse and neon code.

Also fix to assert for the scaled width/height:
in case scaled width/height is odd it should be
incremented by 1 (make it even).

Change-Id: I3a2e40effa53c505f44ef05aaa3132e1b7f57dd5