quantize test: restrict and correct input

quantize test: restrict and correct input

Use only valid values for quantize inputs. These were determined by
looping over vp9_init_quantizer and looking for max and min values.

This allows extending the test to the low bit depth functions which were
not designed to handle all possible inputs but only valid inputs.

Change-Id: I94e1d8863a49ac227845b65c6b50130e10e6319e