Changes

gsm48_cc_tx_setup_set_transaction_id: split out

Move the code for setting the transaction ID to a separate function to
start making gsm48_cc_tx_setup shorter and easier to read. Return -1 on
error instead of rc from mncc_release_ind() as it returns 0 on success.

Make some tweaks while at it:
* Set LOGL_ERROR for the "TX Setup with assigned transaction" error.
* Add a log message for the "could not get a free transaction ID" case.
* Minor formatting tweaks.

Change-Id: I715f12d09570211a98b667c56960309bd326e8d8

gsm48_cc_tx_setup_set_transaction_id: tweak error msg

Reword the message to make it less confusing.

Change-Id: I4007e99b6abd9b2e05945ccdedaac185a2aea19e

gsm48_cc_tx_setup_select_codecs: split out

Change-Id: Ic502f9ed77ea57de4cf6d362c0e7070d9147d6f3

gsm48_cc_tx_setup_set_bearer_cap: split out

Change-Id: I3fe6bb2af90d729bb32cae8f5a1a38dcf8f87eb9

gsm48_cc_tx_setup_encode_msg: split out

Change-Id: I443b4b54c6ad40d852e4c21c896c2d0da5fac239

gsm48_cc_tx_setup: remove extra bearer_cap var

Store the bearer capabilities directly in the transaction, instead of
storing them in a separate variable first, then copying it to the
transaction, then using both the separate variable and the copy in the
transaction later on. The extra variable is not needed and only makes it
more compilicated.

Add an explicit '.transfer = GSM48_BCAP_ITCAP_SPEECH,' while at it in
the speech case. This was already set implicitly because
GSM48_BCAP_ITCAP_SPEECH is 0.

Change-Id: I247ef10923c2875ca75e73046f4b8ed14190d4d2