ARM: dts: kirkwood: fix spelling mistake

Fix a spelling mistake in arch/arm/boot/dts/kirkwood-topkick.dts.
The manufacturer's name is Univer*s*al Scientific Industrial...
Compare with footer of page here:
http://www.usish.com/english/products_topkick1281p2.php



Signed-off-by: Paul Wassi <p.wassi@gmx.at>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>