pcmcia cis: on an out of range CIS read return 0xff, don't just warn

The current code displays warnings but then proceeds to try and reference
the data through the PCMCIA window. Instead return 0xff. This prevents bogus
CIS data sending us off into hyperspace.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>