The previous naming was quite confusing, since the function is not
really checking whether a conversion is needed, but rather whether the
codec has the AMR RTP mode defined explicitly and hence forced.
The previous naming didn't harm because the amr_oa_bwe_convert also
supports the conversion path OA<->OA and BE<->BE.
Hence nowadays the amr_oa_bwe_convert() function is called always if the
dst conn has its codec with AMR RTP mode explicitly set, no matter if
the src and dst conn have the same mode.
Related: SYS#6161
Change-Id: I8dce3038ebccf5e1e37e2908070a67d66693a96f