Introduce write_delta_q_params() function.
Introduce write_delta_q_params() function.

Refactor duplicate code from pack_inter_mode_mvs() and
write_mb_modes_kf().

BUG=aomedia:2044

Change-Id: I4fb3df6121b385eabd8f62139820a37da057b764

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