msm: npu: Add mailbox controller support

In order to prevent GLINK and SMP2P driver sending IPCC irq via
ipcc_mproc mailbox to NPUQ6 when itis in sleep mode, a mailbox
controller is implemented to connect them and control if it's
allowed to send data to ipcc_mproc mailbox to trigger IPCC irq.

Change-Id: Id03a884bda605db4e75cb7dd117b04af7d601f8c
Signed-off-by: Jilai Wang <jilaiw@codeaurora.org>