xilinx_hwicap: remove improper wording in license statement

GPLv2 doesn't allow additional restrictions to be imposed on any
code, so this wording needs to be removed from these files.

Signed-off-by: Stephen Neuendorffer <stephen.neuendorffer@xilinx.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>