ARM: plat-versatile: LEDs initialise to off state

There really is no excuse to turn on all 8 LEDs at boot time, such
that on the Versatile PB/926 we end up with 6 LEDs on continuously
and forever.  We're not a christmas decoration!

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>