drm/bridge: adv7511: Initialize regulators

Maintain a table of regulator names expected by ADV7511 and ADV7533.
Use regulator_bulk_* api to configure these.

Initialize and enable the regulators during probe itself. Controlling
these dynamically is left for later.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1484117547-26417-3-git-send-email-architt@codeaurora.org