drm/i915: Add REG_GENMASK64() and REG_FIELD_GET64()

We treat SSKPD as a 64 bit register. Add the support macros
to define/extract bits in such registers.

v2: Fix 32bit builds

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220211182045.23555-1-ville.syrjala@linux.intel.com


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