Staging: et131x: Fix 2.6.33rc1 regression in et131x

et131x: Fix 12bit wrapping

From: Alan Cox <alan@linux.intel.com>

The 12bit wrap logic conversion is wrong and this shows up for some
memory sizes and layouts of card. Patch it up for now, once the kernel
view of status is cleaned up it'll become two variables and a lot saner.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>