drm/amd/display: remove duplicate include in dcn21 and gpio

'dce110_resource.h' included in 'dcn21_resource.c' is duplicated.
'hw_gpio.h' included in 'hw_factory_dce110.c' is duplicated.

Signed-off-by: Zhang Yunkai <zhang.yunkai@zte.com.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>