drm/i915: Improve modeset debugs

Use the "[CRTC:%d:%s]'/etc. format for some of the modeset debugs
so we know more about what has happened during the modeset state
computation.

Also tweak the connector bpp debug message a bit to make it less
confusing.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220503182242.18797-10-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>