protocol: check the packetization in local cx options

When the local connection options in an MDCX or CRCX request
are parsed, then the packetization interval is not checked.

- Check if the packetization is a multiple of 20ms

see also TTCN3 test: MGCP_Test.TC_crcx_unsupp_packet_intv

Change-Id: I02aaa3042f2a0e32eb4ec6b8753deab7082947a0
Related: OS#2654
1 file changed