amdgpu/dc: fix non-ansi function decls.

smatch reported:
drivers/gpu/drm/amd/amdgpu/../display/dc/bios/dce80/command_table_helper_dce80.c:351:71: warning: non-ANSI function declaration of function 'dal_cmd_tbl_helper_dce80_get_table'
drivers/gpu/drm/amd/amdgpu/../display/dc/bios/dce110/command_table_helper_dce110.c:361:72: warning: non-ANSI function declaration of function 'dal_cmd_tbl_helper_dce110_get_table'
drivers/gpu/drm/amd/amdgpu/../display/dc/bios/dce112/command_table_helper_dce112.c:415:72: warning: non-ANSI function declaration of function 'dal_cmd_tbl_helper_dce112_get_table'
drivers/gpu/drm/amd/amdgpu/../display/dc/bios/dce112/command_table_helper2_dce112.c:415:73: warning: non-ANSI function declaration of function 'dal_cmd_tbl_helper_dce112_get_table2'
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_surface.c:148:34: warning: non-ANSI function declaration of function 'dc_create_gamma'
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_surface.c:178:50: warning: non-ANSI function declaration of function 'dc_create_transfer_func'

This fixes them.

Reviewed-by: Harry Wentland <[e-mail]>
Signed-off-by: Dave Airlie <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/dc/bios/dce110/command_table_helper_dce110.c

···
  * const struct command_table_helper **h - [out] struct of functions
  *
  */
-const struct command_table_helper *dal_cmd_tbl_helper_dce110_get_table()
+const struct command_table_helper *dal_cmd_tbl_helper_dce110_get_table(void)
 {
 	return &command_table_helper_funcs;
 }

drivers/gpu/drm/amd/display/dc/bios/dce112/command_table_helper2_dce112.c

···
  * const struct command_table_helper **h - [out] struct of functions
  *
  */
-const struct command_table_helper *dal_cmd_tbl_helper_dce112_get_table2()
+const struct command_table_helper *dal_cmd_tbl_helper_dce112_get_table2(void)
 {
 	return &command_table_helper_funcs;
 }

drivers/gpu/drm/amd/display/dc/bios/dce112/command_table_helper_dce112.c

···
  * const struct command_table_helper **h - [out] struct of functions
  *
  */
-const struct command_table_helper *dal_cmd_tbl_helper_dce112_get_table()
+const struct command_table_helper *dal_cmd_tbl_helper_dce112_get_table(void)
 {
 	return &command_table_helper_funcs;
 }

drivers/gpu/drm/amd/display/dc/bios/dce80/command_table_helper_dce80.c

···
 		dal_cmd_table_helper_encoder_mode_bp_to_atom,
 };
 
-const struct command_table_helper *dal_cmd_tbl_helper_dce80_get_table()
+const struct command_table_helper *dal_cmd_tbl_helper_dce80_get_table(void)
 {
 	return &command_table_helper_funcs;
 }

drivers/gpu/drm/amd/display/dc/core/dc_surface.c

···
 	*gamma = NULL;
 }
 
-struct dc_gamma *dc_create_gamma()
+struct dc_gamma *dc_create_gamma(void)
 {
 	struct dc_gamma *gamma = kzalloc(sizeof(*gamma), GFP_KERNEL);
 
···
 	kref_put(&tf->refcount, dc_transfer_func_free);
 }
 
-struct dc_transfer_func *dc_create_transfer_func()
+struct dc_transfer_func *dc_create_transfer_func(void)
 {
 	struct dc_transfer_func *tf = kzalloc(sizeof(*tf), GFP_KERNEL);