drm/radeon/dpm: fixup dynamic state adjust for btc (v2)

Use a dedicated copy of the current power state since
we may have to adjust it on the fly.

v2: fix up redundant state sets

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/btc_dpm.h

@@ -33,4 +33,6 @@
 #define BTC_CGULVPARAMETER_DFLT                       0x00040035
 #define BTC_CGULVCONTROL_DFLT                         0x00001450
 
+extern u32 btc_valid_sclk[];
+
 #endif