kirkwood: dns325: Enable 2nd harddrive

The 2nd HD is not enabled in U-Boot on the D-Link DNS325. This patch
sets the responsible GPIO to high, enabling the drive.

Suggested-by: Peter Granilla
Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Tom Rini <trini@konsulko.com>
Reviewed-by: Tony Dinh <mibodhi@gmail.com>