drm/i915: Add separate define for SEL_FETCH_CUR_CTL()

drm/i915: Add separate define for SEL_FETCH_CUR_CTL()

Split the cursor stuff from the rest of the selective fetch
plane registers so that we can collect all cursor registers
in intel_cursor_regs.h. Also take the opportunity to rename
the registers to match the spec.

v2: Pass the correct register offset fpr pipe B (Jani)
    s/mtl+/tgl+/ as that's where this was introduced
    Drop the bogus SEL_FETCH_CUR_CTL_ENABLE bit, the contents
    actually match the normal CUR_CTL register

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240520171459.9661-1-ville.syrjala@linux.intel.com