fix map entry and .h declaration for gsm0808_chan_type_to_speech_codec()

Recent commit 3149b0d076477303a38df735fe579b1b06ee17b2 adds function
gsm0808_chan_type_to_speech_codec() but adds a completely mismatching name in
libosmogsm.map, as well as a definition with a typo in the name.

Fix the entry in libosmogsm.map.

Add the missing 'c' in gsm0808_utils.h

Change-Id: I5a621fa5ef6b632eabbe224f3dd383eacaffb695
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index 36cba39..2da8649 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -162,7 +162,7 @@
 gsm0808_dec_encrypt_info;
 gsm0808_enc_cell_id_list;
 gsm0808_dec_cell_id_list;
-gsm0808_convert_to_speech_codec_type;
+gsm0808_chan_type_to_speech_codec;
 gsm0808_extrapolate_speech_codec;
 
 gsm0858_rsl_ul_meas_enc;