drm/msm/dsi: Implement RPM suspend/resume callbacks

The bus clocks are always enabled/disabled along with the power
domain, so move it to the runtime suspend/resume ops. This cleans
up the clock code a bit. Get rid of the clk_mutex mutex since it
isn't needed.

Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/dsi/dsi.c

@@ -161,12 +161,17 @@ static const struct of_device_id dt_match[] = {
 	{}
 };
 
+static const struct dev_pm_ops dsi_pm_ops = {
+	SET_RUNTIME_PM_OPS(msm_dsi_runtime_suspend, msm_dsi_runtime_resume, NULL)
+};
+
 static struct platform_driver dsi_driver = {
 	.probe = dsi_dev_probe,
 	.remove = dsi_dev_remove,
 	.driver = {
 		.name = "msm_dsi",
 		.of_match_table = dt_match,
+		.pm = &dsi_pm_ops,
 	},
 };