at-spi2-atk: dont inherit features_check

In commit be18dabd:
[ at-spi2: Make X11 support truly optional ]

REQUIRED_DISTRO_FEATURES was dropped, so it does not have to inherit
features_check.bbclass.

Signed-off-by: Ming Liu <ming.liu@toradex.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>