leds: Remove ARCH_KIRKWOOD dependency

mach-kirkwood has been removed, now that kirkwood lives in mach-mvebu.
Use MACH_KIRKWOOD which will be set when kirkwood is built as part of
mach-mvebu.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Bryan Wu <cooloney@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: linux-leds@vger.kernel.org
Link: https://lkml.kernel.org/r/1409417172-6846-5-git-send-email-andrew@lunn.ch


Signed-off-by: Jason Cooper <jason@lakedaemon.net>