ARM: kirkwood: rename kirwood-nsa310-common to 3x0-common

 Rename the include file kirkwood-nsa310-common.dtsi as
 it is now also used for NSA320. There is also an NSA325
 but that appears not to be as similar so is unlikely to
 want to share an include file.

Signed-off-by: Adam Baker <linux@baker-net.org.uk>
Link: https://lkml.kernel.org/r/53447978.2020206@baker-net.org.uk


Acked-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>