The gsm_subscriber_connection->encr is never used. Use it.
When sending the Ciphering Mode Command, populate the encryption key.
When receivint the Ciphering Mode Complete, populate the chosen alg_id.
Out of paranoia, store the enc key only if the size is large enough.
Hence the vty_dump_one_conn() now reports the actually chosen A5 algorithm ID
used.
For 3G connections, though, this will still remain 0 in the VTY, since there is
no explicit A5 algorithm negotiated on UTRAN. (Security Mode Command and
Security Mode Complete instead of the GERAN Ciphering.)
(Note, 'struct gsm_encr encr' will be renamed to 'struct geran_encr geran_encr'
in Idc7ca9da1aa13ae16f5db2cb1024676cbc770820)
Change-Id: Ice2c470c360612249f97301944c6fdf9443c7dce
b0779bbcab