mailbox: add Tegra186 HSP driver

Tegra186's HSP module implements doorbells, mailboxes, semaphores, and
shared interrupts. This patch provides a driver for HSP, and hooks it
into the mailbox API. Currently, only doorbells are supported.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>
6 files changed