Set the CALLERID(dnid-num-plan) for incoming ISDN calls.

The CALLEDTON channel variable is set for incoming ISDN calls to the lower
7 bits of the Q.931 type-of-number/numbering-plan octet.  The
CALLERID(dnid-num-plan) should have the same value.

(closes issue ASTERISK-21248)
Reported by: rmudgett


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/1.8@383796 f38db490-d61c-443f-a65b-d21fe96a405b