The for loop in osmo_amr_bwe_to_oa, that converts the body part of the
AMR payload runs one byte too far. This may cause that some of the
padding bits in the end are not set to zero. The loop is designed to
convert n-1 bytes and the nth byte is done separately at the end.
Change-Id: I91e755b83aaac722079879c026d913cc446812d1