Changes

rtp2trau_hr16: use osmo_hr_check_sid()

The code in libosmotrau previously used its own local function
to check incoming 112-bit HRv1 frames against the possibility of
perfect SID (all 79 bits of SID field set to 1).  However, there is
a public API function in libosmocodec that does the exact same job
- use the common library function.

Until recently, the implementation of osmo_hr_check_sid() in
libosmocodec was quite inefficient (the local version in libosmotrau
was faster) and contained a logic error in the handling of zero-length
input in the place of a received frame.  However, both of these
defects in osmo_hr_check_sid() have now been fixed in libosmocore,
clearing the way for this common library function to be used.

Depends: Ib14204102c03c14d6c5aab42b0ffbef2c3dda3fd (libosmocore)
Change-Id: Ia8fe7e9ea65fadf7f5c136355ca8c24c89f09ef2

trau_rtp_conv.c cosmetic: fix typo in name of static function

Change I7a6d13d406484c01210594bb6d2f0aff7c1341ab introduced
a static function in src/trau/trau_rtp_conv.c that was intended
to be named twts002_hr16_set_extra_flags().  However, a typo
crept in unnoticed, and the patch was merged with this function
name misspelled as twtw002_hr16_set_extra_flags().  Fix it.

Related: OS#6448
Change-Id: I63bb678f7a1f26fefba070ddc10850db24cb88b3