Merge tag 'mailbox-v4.19' of git://git.linaro.org/landing-teams/working/fujitsu/integ...

Pull mailbox updates from Jassi Brar:

 - xgene: potential null pointer fix

 - omap: switch to spdx license and use of_device_get_match_data() to
   match data

 - ti-msgmgr: cleanup and optimisation. New TI specific feature - secure
   proxy thread.

 - mediatek: add driver for CMDQ controller.

 - nxp: add driver for MU controller

* tag 'mailbox-v4.19' of git://git.linaro.org/landing-teams/working/fujitsu/integration:
  mailbox: Add support for i.MX messaging unit
  dt-bindings: mailbox: imx-mu: add generic MU channel support
  dt-bindings: arm: fsl: add mu binding doc
  mailbox: add MODULE_LICENSE() for mtk-cmdq-mailbox.c
  mailbox: mediatek: Add Mediatek CMDQ driver
  dt-bindings: soc: Add documentation for the MediaTek GCE unit
  mailbox: ti-msgmgr: Add support for Secure Proxy
  dt-bindings: mailbox: Add support for secure proxy threads
  mailbox: ti-msgmgr: Move the memory region name to descriptor
  mailbox: ti-msgmgr: Change message count mask to be descriptor based
  mailbox: ti-msgmgr: Allocate Rx channel resources only on request
  mailbox: ti-msgmgr: Get rid of unused structure members
  mailbox/omap: use of_device_get_match_data() to get match data
  mailbox/omap: switch to SPDX license identifier
  mailbox: xgene-slimpro: Fix potential NULL pointer dereference