drm/rect: Add drm_rect_overlap()

Check if two rectangles overlap.
It's a bit similar to drm_rect_intersect() but this won't modify
the rectangle.
Simplifies a bit drm_panic.

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240822073852.562286-3-jfalempe@redhat.com