MAINTAINERS: Remove tree entry for rtl8180

This entry is not needed. Remove it.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Link: https://lore.kernel.org/r/20230804222438.16076-3-Larry.Finger@lwfinger.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>