drm/amd/pm/powerplay/hwmgr/hwmgr: Move 'smu8_init_function_pointers()' prototype to shared header

Fixes the following W=1 kernel build warning(s):

Cc: Evan Quan <evan.quan@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/pm/inc/hwmgr.h

@@ -828,5 +828,6 @@ int hwmgr_handle_task(struct pp_hwmgr *hwmgr,
 
 #define PHM_ENTIRE_REGISTER_MASK 0xFFFFFFFFU
 
+int smu8_init_function_pointers(struct pp_hwmgr *hwmgr);
 
 #endif /* _HWMGR_H_ */

drivers/gpu/drm/amd/pm/powerplay/hwmgr/hwmgr.c

@@ -47,7 +47,6 @@ extern const struct pp_smumgr_func smu10_smu_funcs;
 extern const struct pp_smumgr_func vega20_smu_funcs;
 
 extern int smu7_init_function_pointers(struct pp_hwmgr *hwmgr);
-extern int smu8_init_function_pointers(struct pp_hwmgr *hwmgr);
 extern int vega10_hwmgr_init(struct pp_hwmgr *hwmgr);
 extern int vega12_hwmgr_init(struct pp_hwmgr *hwmgr);
 extern int vega20_hwmgr_init(struct pp_hwmgr *hwmgr);