drm/i915: Eliminate intel_compute_sagv_mask()

intel_compute_sagv_mask() has become pointless. Just inline
its contents into the existing loop in skl_compute_wm().

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250326162544.3642-15-ville.syrjala@linux.intel.com


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