drm/radeon: fix UPLL_REF_DIV_MASK definition

Stupid copy & paste error over all generations.

Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/rv770d.h b/drivers/gpu/drm/radeon/rv770d.h
index 6a52b20..85b1626 100644
--- a/drivers/gpu/drm/radeon/rv770d.h
+++ b/drivers/gpu/drm/radeon/rv770d.h
@@ -45,7 +45,7 @@
 #	define UPLL_BYPASS_EN_MASK			0x00000004
 #	define UPLL_CTLREQ_MASK				0x00000008
 #	define UPLL_REF_DIV(x)				((x) << 16)
-#	define UPLL_REF_DIV_MASK			0x001F0000
+#	define UPLL_REF_DIV_MASK			0x003F0000
 #	define UPLL_CTLACK_MASK				0x40000000
 #	define UPLL_CTLACK2_MASK			0x80000000
 #define CG_UPLL_FUNC_CNTL_2				0x71c