um: Update maintainers file entry

- Remove stale fs/hppfs/ reference
- Point to our patchwork queue
Signed-off-by: Richard Weinberger <richard@nod.at>

MAINTAINERS

@@ -15803,13 +15803,13 @@ M:	Jeff Dike <jdike@addtoit.com>
 M:	Richard Weinberger <richard@nod.at>
 L:	linux-um@lists.infradead.org
 W:	http://user-mode-linux.sourceforge.net
+Q:	https://patchwork.ozlabs.org/project/linux-um/list/
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml.git
 S:	Maintained
 F:	Documentation/virtual/uml/
 F:	arch/um/
 F:	arch/x86/um/
 F:	fs/hostfs/
-F:	fs/hppfs/
 
 USERSPACE COPYIN/COPYOUT (UIOVEC)
 M:	Alexander Viro <viro@zeniv.linux.org.uk>