drm/amd/display: include missing headers

Add missing headers to solve the following warnings from sparse:

drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn20/dcn20_fpu.c:656:17: warning: symbol 'ddr4_wm_table_gs' was not declared. Should it be static?
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn20/dcn20_fpu.c:693:17: warning: symbol 'lpddr4_wm_table_gs' was not declared. Should it be static?
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn20/dcn20_fpu.c:730:17: warning: symbol 'lpddr4_wm_table_with_disabled_ppt' was not declared. Should it be static?
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn20/dcn20_fpu.c:767:17: warning: symbol 'ddr4_wm_table_rn' was not declared. Should it be static?
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn20/dcn20_fpu.c:804:17: warning: symbol 'ddr4_1R_wm_table_rn' was not declared. Should it be static?
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn20/dcn20_fpu.c:841:17: warning: symbol 'lpddr4_wm_table_rn' was not declared. Should it be static?
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn301/dcn301_fpu.c:217:17: warning: symbol 'ddr4_wm_table' was not declared. Should it be static?
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn301/dcn301_fpu.c:254:17: warning: symbol 'lpddr5_wm_table' was not declared. Should it be static?
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn31/dcn31_fpu.c:53:30: warning: symbol 'dcn3_1_ip' was not declared. Should it be static?
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn31/dcn31_fpu.c:197:30: warning: symbol 'dcn3_15_ip' was not declared. Should it be static?
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn31/dcn31_fpu.c:293:30: warning: symbol 'dcn3_16_ip' was not declared. Should it be static?

Fixes: 1a340825 ("drm/amd/display: move FPU code on dcn21 clk_mgr")
Fixes: 5085e036 ("drm/amd/display: move FPU code from dcn301 clk mgr to DML folder")
Fixes: 26f4712a ("drm/amd/display: move FPU related code from dcn31 to dml/dcn31 folder")
Fixes: fa896297 ("drm/amd/display: move FPU related code from dcn315 to dml/dcn31 folder")
Fixes: 3f8951cc

 ("drm/amd/display: move FPU related code from dcn316 to dml/dcn31 folder")
Signed-off-by: Magali Lemes <magalilemes00@gmail.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Reviewed-by: Maíra Canal <mairacanal@riseup.net>
Reviewed-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>