drm/bridge: adv7511: Enable HPD interrupts to support hotplug and improve monitor detection

On some adv7511 implementations, we can get some spurious
disconnect signals which can cause monitor probing to fail.

This patch enables HPD (hot plug detect) interrupt support
which allows the monitor to be properly re-initialized when
the spurious disconnect signal goes away.

This also enables proper hotplug support.

Cc: David Airlie <airlied@linux.ie>
Cc: Archit Taneja <architt@codeaurora.org>
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: dri-devel@lists.freedesktop.org
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Originally-by: Archit Taneja <architt@codeaurora.org>
[jstultz: Added proper commit message]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1484614372-15342-4-git-send-email-john.stultz@linaro.org