MAINTAINERS: remove obsolete file entry in TUN/TAP DRIVER

Commit 65eaac5 ("um: Remove obsolete legacy network transports")
removes the directory arch/um/os-Linux/drivers/, but misses to remove the
file entry in TUN/TAP DRIVER referring to that directory.

Remove this obsolete file entry. While at it, put the section name in
capital letters.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Reviewed-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20250507071004.35120-1-lukas.bulwahn@redhat.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Author: bulwahn

MAINTAINERS

@@ -24694,13 +24694,12 @@ L:	linux-parisc@vger.kernel.org
 S:	Orphan
 F:	drivers/net/ethernet/dec/tulip/
 
-TUN/TAP driver
+TUN/TAP DRIVER
 M:	Willem de Bruijn <willemdebruijn.kernel@gmail.com>
 M:	Jason Wang <jasowang@redhat.com>
 S:	Maintained
 W:	http://vtun.sourceforge.net/tun
 F:	Documentation/networking/tuntap.rst
-F:	arch/um/os-Linux/drivers/
 F:	drivers/net/tap.c
 F:	drivers/net/tun*