Run the AT modem commands through debugd.

This is necessary because communication with the serial interface
needs root access.

BUG=chrome-os-partner:17809
TEST=tested by issuing the relevant 'modem' commands in crosh
CQ-DEPEND=Iecea0ab5aeb2907ae463fe9a6f1aa83b5632091a

Change-Id: Ic43069080726d62447d5b8d41790ec5340639faa
Reviewed-on: https://gerrit.chromium.org/gerrit/44420
Tested-by: Darin Petkov <[email protected]>
Reviewed-by: Elly Jones <[email protected]>
Reviewed-by: Jorge Lucangeli Obes <[email protected]>
Commit-Queue: Darin Petkov <[email protected]>
1 file changed