drm/vc4: dsi: Switch to devm_drm_of_get_bridge

drm/vc4: dsi: Switch to devm_drm_of_get_bridge

BugLink: https://bugs.launchpad.net/bugs/1990162
[ Upstream commit a43dd76bacd0d5441a4c84f60d64bdfaedc95bac ]

The new devm_drm_of_get_bridge removes most of the boilerplate we
have to deal with. Let's switch to it.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210910130941.1740182-4-maxime@cerno.tech
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>