drm/rockchip: Explicitly include bits header

Driver makes use of the BIT() macro, but relies on the bits header being
implicitly included.

Explicitly pull the header in to avoid potential build failures in some
configurations.

While at it, reorder include directives alphabetically.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240807-b4-rk3588-bridge-upstream-v3-4-60d6bab0dc7c@collabora.com