BSSMAP: tweaks

Change two instances of Speech Version values to enum gsm0808_permitted_speech.
It is often not trivial to find the right values for a uint8_t member, giving
the enum name makes it a lot easier/safer to use.

In gsm0808_create_handover_required(), use msgb_tv_put() so that the enum's
storage size doesn't matter. (Already used for handover_performed)

Fix typo in doc of gsm0808_create_handover_required().

Change-Id: I6387836bab76e1fa42daa0f42ab94fc14b70b112
diff --git a/TODO-RELEASE b/TODO-RELEASE
index 7c81e32..db3be49 100644
--- a/TODO-RELEASE
+++ b/TODO-RELEASE
@@ -19,3 +19,5 @@
 		osmo_quote_str_buf()	  truncated string. This is no longer the case. e.g. a string 'truncated' in a
 					  9-char buffer used to print '"trunca"\0', which now becomes '"truncat\0'.
 libosmocore	osmo_quote_str_buf2()	New function signature similar to snprintf(), for use with OSMO_STRBUF_APPEND().
+libosmogsm	gsm0808_handover_required	Storage size changed, speech_version_used now an enum.
+		gsm0808_handover_performed	Storage size changed, speech_version_chosen now an enum.