drm/radeon/dpm: fix a typo in the rv6xx mclk setup

Need to set high for the last two entries.  Looks
like a copy and paste typo.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/rv6xx_dpm.c b/drivers/gpu/drm/radeon/rv6xx_dpm.c
index 65e33f3..b1c2a62 100644
--- a/drivers/gpu/drm/radeon/rv6xx_dpm.c
+++ b/drivers/gpu/drm/radeon/rv6xx_dpm.c
@@ -819,7 +819,7 @@
 		 POWERMODE1(calculate_memory_refresh_rate(rdev,
 							  pi->hw.sclks[R600_POWER_LEVEL_MEDIUM])) |
 		 POWERMODE2(calculate_memory_refresh_rate(rdev,
-							  pi->hw.sclks[R600_POWER_LEVEL_MEDIUM])) |
+							  pi->hw.sclks[R600_POWER_LEVEL_HIGH])) |
 		 POWERMODE3(calculate_memory_refresh_rate(rdev,
 							  pi->hw.sclks[R600_POWER_LEVEL_HIGH])));
 	WREG32(ARB_RFSH_RATE, arb_refresh_rate);