ipmid: channel: add max transfer size property

Each channel can have a different maximum transfer size. This should be
exposed so that it is easier to tell how many bytes it is possible to
send or receive on a given channel.

Change-Id: Ie277eb7a802edc1deeefe201a7560d371920f519
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>
4 files changed