ARM: multi_v5_defconfig: Enable recommended options for systemd

Enable FHANDLE, CGROUPS, BLK_DEV_BSG and DEVTMPFS as recommended by
systemd (which also matches the multi_v7 defconfig). Also enable IPV6,
which defaults to 'y' by now.

Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>