hlr.c: replace deprecated osmo_gsup_get_err_msg_type()

Use OSMO_GSUP_TO_MSGT_ERROR() instead. The other function has been
deprecated in [1].

Remove the < 0 return check, because the macro doesn't do any error
handling. It relies on all "request" messages having an appropriate
"error" message, which is part of the GSUP spec now (see [2]).

[1] change-id I46d9f2327791978710e2f90b4d28a3761d723d8f (libosmocore)
[2] change-id Iec1b4ce4b7d8eb157406f006e1c4241e8fba2cd6 (osmo-gsm-manuals)

Change-Id: I5435ec4c29d6acee814c33499c68d18aaa91d4fb
1 file changed