MAINTAINERS: Fix F: in "VFIO-USER"

The commit adding the section added two bad F: lines: include/hw/vfio-user/ never existed, and subprojects/libvfio-user had long been replaced by subprojects/libvfio.wrap. Drop the former, and correct the latter. Fixes: 9fca2b7d70 (vfio-user: add vfio-user class and container, 2025-06-25) Cc: John Levon <john.levon@nutanix.com> Cc: Thanos Makatos <thanos.makatos@nutanix.com> Cc: Cédric Le Goater <clg@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Cédric Le Goater <clg@redhat.com> Reviewed-by: John Levon <john.levon@nutanix.com> Message-ID: <20260603064032.3733394-36-armbru@redhat.com>