ARM: mvebu: clean-up unneeded kconfig selects

Multi-platform support implies all these options are already selected and
individual platforms don't need to select them.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Gregory Clement <gregory.clement@free-electrons.com>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>