um: link vmlinux with -no-pie

commit 883354afbc109c57f925ccc19840055193da0cc0 upstream.

Debian's gcc defaults to pie. The global Makefile already defines the -fno-pie option.
Link UML dynamic kernel image also with -no-pie to fix the build.

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
Cc: Bernie Innocenti <codewiz@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Tkkg1994 <luca@grifodev.ch>