Use gsm48_encode_ra() for RAI encoding

It has stricter type signature which increase the chance of spotting
misuse either via compiler warning or with automated scan. This also
paves the way for gsm48_construct_ra() deprecation in libosmocore.

Change-Id: I2c0f082dc7214ed57a40dad0788e34b838dfac97
Related: OS#1640
1 file changed