Pull mailbox updates from Jassi Brar:

 - mailbox api: allow direct registration to a channel and convert omap
   and pcc to use mbox_bind_client

 - omap and hi6220 : use of_property_read_bool

 - test: fix double-free and use spinlock header

 - rockchip and bcm-pdc: drop of_match_ptr

 - mpfs: change config symbol

 - mediatek gce: support MT6795

 - qcom apcs: consolidate of_device_id and support IPQ9574

* tag 'mailbox-v6.4' of git://git.linaro.org/landing-teams/working/fujitsu/integration:
  dt-bindings: mailbox: qcom: add compatible for IPQ9574 SoC
  mailbox: qcom-apcs-ipc: do not grow the of_device_id
  dt-bindings: mailbox: qcom,apcs-kpss-global: use fallbacks for few variants
  dt-bindings: mailbox: mediatek,gce-mailbox: Add support for MT6795
  mailbox: mpfs: convert SOC_MICROCHIP_POLARFIRE to ARCH_MICROCHIP_POLARFIRE
  mailbox: bcm-pdc: drop of_match_ptr for ID table
  mailbox: rockchip: drop of_match_ptr for ID table
  mailbox: mailbox-test: Fix potential double-free in mbox_test_message_write()
  mailbox: mailbox-test: Explicitly include header for spinlock support
  mailbox: Use of_property_read_bool() for boolean properties
  mailbox: pcc: Use mbox_bind_client
  mailbox: omap: Use mbox_bind_client
  mailbox: Allow direct registration to a channel