const-ify make segment ops structures
There is no reason to keep the segment ops structures writable.

@@ -343,11 +343,11 @@
 #endif
 
 /*
  *  extern hacks
  */
-extern struct seg_ops segdev_ops;
+extern const struct seg_ops segdev_ops;
 extern int ignore_hardware_nodes;       /* force flag from ddi_impl.c */
 #ifdef  DDI_MAP_DEBUG
 extern int ddi_map_debug_flag;
 #define ddi_map_debug   if (ddi_map_debug_flag) prom_printf
 #endif