[ARM] 3344/1: NSLU2: beeper support

Patch from Alessandro Zummo

This patch adds support for the beeper
embedded in the NSLU2 to the machine setup code.

Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Rod Whitby <rod@whitby.id.au>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>