drm/i915: Clean up bxt/glk PLL registers

Use REG_BIT() & co. for bxt/glk PLL registers.

v2: Reorder a few bits for consistency

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220307233940.4161-4-ville.syrjala@linux.intel.com


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