drm/rockchip: vop: Fix reset of state in duplicate state crtc funcs

struct rockchip_crtc_state members such as output_type, output_bpc and
enable_afbc is always reset to zero in the atomic_duplicate_state crtc
funcs.

Fix this by using kmemdup on the subclass rockchip_crtc_state struct.

Fixes: 4e257d9e

 ("drm/rockchip: get rid of rockchip_drm_crtc_mode_config")
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230621223311.2239547-2-jonas@kwiboo.se