base

CEC: Support sendStandby() for MHL device

Changed so that the API sendStandby() transform the request to
a MHL subcommand if the call is done against a MHL device.

Also hooked up the dump() to print out information on MHL.

Bug: 18451257
Change-Id: I1927855e0e4c45a731f0fd97ba572bfc2a894557