fix codec mapping for GSM-HR

The cfg bits are for AMR-HR, not GSM-HR. The function
gsm0808_enc_speech_codec_list2() will return -EINVAL when it encounters
GSM-HR with non-zero cfg bits.

It appears this mapping was never used before, and my testing of call
re-assignment to match MT's codecs (it allows more than just the
assigned codec, because it can re-assign) has uncovered this bug
via MSC_Tests.TC_ho_inter_msc_out. I don't fully understand all the
details why we didn't see this before; anyway, the fix is obvious.

Change-Id: I19cff847a0f618ad000d12c1df54c55ef2f79699

src/libmsc/codec_mapping.c

@@ -105,7 +105,6 @@ const struct codec_mapping codec_map[] = {
 		.gsm0808_speech_codec = {
 			.fi = true,
 			.type = GSM0808_SCT_HR1,
-			.cfg = GSM0808_SC_CFG_DEFAULT_HR_AMR,
 		},
 		.perm_speech = GSM0808_PERM_HR1,
 		.frhr = CODEC_FRHR_HR,