accel/amdxdna: Support hardware mailbox

The hardware mailboxes are used by the driver to submit requests to
firmware and receive the completion notices from hardware.

Initially, a management mailbox channel is up and running. The driver may
request firmware to create/destroy more channels dynamically through
management channel.

Add driver internal mailbox interfaces.
  - create/destroy a mailbox channel instance
  - send a message to the firmware through a specific channel
  - wait for a notification from the specific channel

Co-developed-by: George Yang <George.Yang@amd.com>
Signed-off-by: George Yang <George.Yang@amd.com>
Co-developed-by: Min Ma <min.ma@amd.com>
Signed-off-by: Min Ma <min.ma@amd.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241118172942.2014541-4-lizhi.hou@amd.com