The module param permsissions should bw read-only, not writable.

From: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: James K Lewis <jklewis@us.ibm.com>
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>