drm/rockchip: dw_hdmi_qp: Use bit macros for RK3576 regs

drm/rockchip: dw_hdmi_qp: Use bit macros for RK3576 regs

For consistency and improved readability, redefine a few RK3576 specific
register configurations by relying on GENMASK() and unshifted values for
color depth and output format.  Those are not used at the moment, but
will be needed soon to support the related features.

While at it, drop a few other defines which are unlikely to be ever
required.

Acked-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20251021-rk3588-10bpc-v3-4-3d3eed00a6db@collabora.com