bus: mvebu-mbus: fix support of MBus window 13

On Armada XP, 375 and 38x the MBus window 13 has the remap capability,
like windows 0 to 7. However, the mvebu-mbus driver isn't currently
taking into account this special case, which means that when window 13
is actually used, the remap registers are left to 0, making the device
using this MBus window unavailable.

As a minimal fix for stable, don't use window 13. A full fix will
follow later.

Fixes: fddddb52

 ("bus: introduce an Marvell EBU MBus driver")
Cc: <stable@vger.kernel.org> # v3.10+
Reviewed-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>