Cast Integer Argument To Unsigned Char

The member reg in the peercnt structure is an unsigned char and peercnt_modify()
is expecting an unsigned char argument which gets assigned to peercnt->reg.

This patch fixes that by casting the integer argument being passed to
peercnt_modify to unsigned char.
........

Merged revisions 400314 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 400315 from http://svn.asterisk.org/svn/asterisk/branches/11
........

Merged revisions 400316 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@400317 65c4cc65-6c06-0410-ace0-fbb531ad65f3