drm/i915/overlay: Remove redundant drm_rect_visible() use

The drm_rect_intersect() already returns if the intersection is visible
or not, so the use of drm_rect_visible() is duplicate.

Signed-off-by: Arthur Grillo <arthurgrillo@riseup.net>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230325172719.92102-1-arthurgrillo@riseup.net