ARM: dts: armada-385-linksys: disk-activity trigger for all

Commit a4ee7e18 ("ARM: dts: armada: Add default trigger for sata
led") adds the default trigger to individual boards, move it to
armada-385-linksys.dtsi which effectively enables the definition for
the WRT1900ACS (Shelby) as well as for future boards.

Signed-off-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>