use NULL getmemid segop as a shorthand for ENODEV
Instead of forcing every segment driver to implement a dummy function to
return (hopefully) ENODEV, handle NULL getmemid segop function pointer as
"return ENODEV" shorthand.

*** 91,101 ****
  static int      segkp_unlock(struct hat *hat, struct seg *seg, caddr_t vaddr,
                          size_t len, struct segkp_data *kpd, uint_t flags);
  static int      segkp_load(struct hat *hat, struct seg *seg, caddr_t vaddr,
                          size_t len, struct segkp_data *kpd, uint_t flags);
  static struct   segkp_data *segkp_find(struct seg *seg, caddr_t vaddr);
- static int      segkp_getmemid(struct seg *seg, caddr_t addr, memid_t *memidp);
  
  /*
   * Lock used to protect the hash table(s) and caches.
   */
  static kmutex_t segkp_lock;
--- 91,100 ----
*** 143,153 ****
          .fault          = segkp_fault,
          .checkprot      = segkp_checkprot,
          .kluster        = segkp_kluster,
          .dump           = segkp_dump,
          .pagelock       = segkp_pagelock,
-         .getmemid       = segkp_getmemid,
  };
  
  
  static void segkpinit_mem_config(struct seg *);
  
--- 142,151 ----
*** 1359,1375 ****
      struct page ***ppp, enum lock_type type, enum seg_rw rw)
  {
          return (ENOTSUP);
  }
  
- /*ARGSUSED*/
- static int
- segkp_getmemid(struct seg *seg, caddr_t addr, memid_t *memidp)
- {
-         return (ENODEV);
- }
- 
  #include <sys/mem_config.h>
  
  /*ARGSUSED*/
  static void
  segkp_mem_config_post_add(void *arg, pgcnt_t delta_pages)
--- 1357,1366 ----