drm/radeon/kms: use tracked values for sclk and mclk

Rather than calling get_memory_clock and get_engine_clock,
used the tracked values from the pm code.  Calling the tables
adds additional latency in the modesetting and pm paths.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon_i2c.c b/drivers/gpu/drm/radeon/radeon_i2c.c
index 0416804..6a13ee3 100644
--- a/drivers/gpu/drm/radeon/radeon_i2c.c
+++ b/drivers/gpu/drm/radeon/radeon_i2c.c
@@ -213,7 +213,7 @@
 
 static u32 radeon_get_i2c_prescale(struct radeon_device *rdev)
 {
-	u32 sclk = radeon_get_engine_clock(rdev);
+	u32 sclk = rdev->pm.current_sclk;
 	u32 prescale = 0;
 	u32 nm;
 	u8 n, m, loop;