dbus-test: Remove EXTRA_OECONF_X configs

X specific configs are already handled through PACKAGECONFIG:
PACKAGECONFIG ??= "${@bb.utils.filter('DISTRO_FEATURES', 'systemd x11', d)}"
...
PACKAGECONFIG[x11] = "--with-x --enable-x11-autolaunch,--without-x
                      --disable-x11-autolaunch, virtual/libx11 libsm"

Remove duplicated EXTRA_OECONF_X args.

Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>