Add /proc/scsi to masked paths

This is writeable, and can be used to remove devices. Containers do
not need to know about scsi devices.

Signed-off-by: Justin Cormack <justin.cormack@docker.com>
diff --git a/oci/defaults.go b/oci/defaults.go
index 0cc07ff..4188071 100644
--- a/oci/defaults.go
+++ b/oci/defaults.go
@@ -119,6 +119,7 @@
 			"/proc/timer_list",
 			"/proc/timer_stats",
 			"/proc/sched_debug",
+			"/proc/scsi",
 		},
 		ReadonlyPaths: []string{
 			"/proc/asound",