drm/amd/display: Modify comments to match the code

[Why]
This line of code was modified. However, comments
remained unchanged. As a result, comments and code are
mismatching.

[How]
Modifying comments to reflect code. At the same time,
explaining why the value was changed from 200ms to
3000ms.
Signed-off-by: Zhan Liu <zhan.liu@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dc_helper.c

@@ -485,7 +485,12 @@ void generic_reg_wait(const struct dc_context *ctx,
 		return;
 	}
 
-	/* something is terribly wrong if time out is > 200ms. (5Hz) */
+	/*
+	 * Something is terribly wrong if time out is > 3000ms.
+	 * 3000ms is the maximum time needed for SMU to pass values back.
+	 * This value comes from experiments.
+	 *
+	 */
 	ASSERT(delay_between_poll_us * time_out_num_tries <= 3000000);
 
 	for (i = 0; i <= time_out_num_tries; i++) {