Rename write_bitdepth_colorspace_sampling.
Rename write_bitdepth_colorspace_sampling.

Rename write_bitdepth_colorspace_sampling to write_color_config to match
the renaming of the corresponding av1_read_bitdepth_colorspace_sampling
on the decoder side in commit a19fdce62ef2a52bb7e2b9b34d84506c378c0122.

BUG=aomedia:1899

Change-Id: I05c1ba99243e6c549c4a4a80ebc757f433c8767a

GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom