drm/amd/powerplay: Add read_sensor() callback to hwmgr (v3)

Provides standardized interface to read various sensors.
The API is extensible (by adding to the end of the
amd_pp_sensors enumeration list.

Support has been added to Carrizo/smu7

(v2) Squashed the two sensor patches into one.
(v3) Updated to apply to smu7_hwmgr instead

Signed-off-by: Tom St Denis <tom.stdenis@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/amd/powerplay/inc/hwmgr.h b/drivers/gpu/drm/amd/powerplay/inc/hwmgr.h
index c9628b4..fcd4545 100644
--- a/drivers/gpu/drm/amd/powerplay/inc/hwmgr.h
+++ b/drivers/gpu/drm/amd/powerplay/inc/hwmgr.h
@@ -359,6 +359,7 @@
 	int (*set_sclk_od)(struct pp_hwmgr *hwmgr, uint32_t value);
 	int (*get_mclk_od)(struct pp_hwmgr *hwmgr);
 	int (*set_mclk_od)(struct pp_hwmgr *hwmgr, uint32_t value);
+	int (*read_sensor)(struct pp_hwmgr *hwmgr, int idx, int32_t *value);
 };
 
 struct pp_table_func {