drm/tegra: dsi: fix device leak on probe

drm/tegra: dsi: fix device leak on probe

Make sure to drop the reference taken when looking up the companion
(ganged) device and its driver data during probe().

Note that holding a reference to a device does not prevent its driver
data from going away so there is no point in keeping the reference.

Fixes: e94236cde4d5 ("drm/tegra: dsi: Add ganged mode support")
Fixes: 221e3638feb8 ("drm/tegra: Fix reference leak in tegra_dsi_ganged_probe")
Cc: stable@vger.kernel.org	# 3.19: 221e3638feb8
Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patch.msgid.link/20251121164201.13188-1-johan@kernel.org