Pull more mailbox updates from Jassi Brar:
"Device tree bindings and driver for TI's Message-Manager controller.
Due to some last minute cosmetic changes, the driver was not included
in the first pull request, otherwise the driver has been reviewed
twice"
* 'mailbox-for-next' of git://git.linaro.org/landing-teams/working/fujitsu/integration:
mailbox: Introduce TI message manager driver
Documentation: dt: mailbox: Add TI Message Manager