staging: ramster: delete the driver

Turns out it's not quite ready to be included, thanks to some other work
done in the zcache and zram code, which breaks this driver.

So, delete it for now, per the recommendation of Dan.

Acked-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>