drm/rockchip: vop2: Drop superfluous include

The rockchip_drm_fb.h header contains just a single function which is
not directly used by the VOP2 driver.  Drop the unnecessary include.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240104143951.85219-1-cristian.ciocaltea@collabora.com