ARM: mvebu: don't select CONFIG_NEON

CONFIG_NEON is meant to be user-selectable. Turning it on
unconditionally means we can't build a smaller kernel when
we don't need it, and causes build errors if CONFIG_VFP
is not also enabled.

To still have neon enabled however, we need to turn it on
now in multi_v7_defconfig and mvebu_v7_defconfig.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Jason Cooper <jason@lakedaemon.net>
Acked-by: Gregory Clement <gregory.clement@free-electrons.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>