mailbox: apcs-ipc: Add support for sdm855

The qcom-apcs-ipc-mailbox driver maps the shared apps
register to trigger interrupts to remote subsystems. This
change adds the correct configuration for sdm855.

Change-Id: I5bbff9d454500315980e86c201eea8aa17454db3
Signed-off-by: Chris Lew <clew@codeaurora.org>