megaraid_sas: remove sysfs poll_mode_io world writeable permissions

megaraid_sas: remove sysfs poll_mode_io world writeable permissions

commit bb7d3f24c71e528989501617651b669fbed798cb upstream.

/sys/bus/pci/drivers/megaraid_sas/poll_mode_io defaults to being
world-writable, which seems bad (letting any user affect kernel driver
behavior).

This turns off group and user write permissions, so that on typical
production systems only root can write to it.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>