libsoup-2.4: remove obsolete intltool dependency

This hasn't been needed since libsoup 2.65.2.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 250a3f9a)
Signed-off-by: Steve Sakoman <steve@sakoman.com>