drm/mediatek: dsi: Simplify with dev_err_probe and remove gotos

Most of the functions that are called in the probe callback are
devm managed, or all but mipi_dsi_host_register(): simplify the probe
function's error paths with dev_err_probe() and remove the lonely
instance of `goto err_unregister_host` by just directly calling the
mipi_dsi_host_unregister() function in the devm_request_irq() error
path, allowing to also remove the same label.

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20240215085316.56835-8-angelogioacchino.delregno@collabora.com/


Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>