drm/bridge: Put Kconfig entries in a separate menu

Put the Kconfig entries for bridge drivers into a separate menu so that
they are automatically grouped and don't clutter up the top-level menu.

While at it, move the bridge menu towards the end of the top-level menu
where the panel menu is already located.

Signed-off-by: Thierry Reding <treding@nvidia.com>

diff --cc drivers/gpu/drm/Kconfig
Simple merge

diff --cc drivers/gpu/drm/bridge/Kconfig
Simple merge