ARM: dts: mvebu: armada-390: add missing compatibility string and bracket

commit 061492cf upstream.

The armada-390.dtsi was broken since the first patch which adds Device Tree
files for Armada 39x SoC was introduced.

Signed-off-by: Grzegorz Jaszczyk <jaz@semihalf.com>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Fixes 538da83d ("ARM: mvebu: add Device Tree files for Armada 39x SoC and board")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>