drm/amd/pm/powerplay/hwmgr/vega10_processpptables: Make function invoked by reference static

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

 drivers/gpu/drm/amd/amdgpu/../pm/powerplay/hwmgr/vega10_processpptables.c:1148:5: warning: no previous prototype for ‘vega10_pp_tables_initialize’ [-Wmissing-prototypes]

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: "Gustavo A. R. Silva" <gustavoars@kernel.org>
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/powerplay/hwmgr/vega10_processpptables.c

@@ -1145,7 +1145,7 @@ static int init_dpm_2_parameters(
 	return result;
 }
 
-int vega10_pp_tables_initialize(struct pp_hwmgr *hwmgr)
+static int vega10_pp_tables_initialize(struct pp_hwmgr *hwmgr)
 {
 	int result = 0;
 	const ATOM_Vega10_POWERPLAYTABLE *powerplay_table;