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.

@@ -91,11 +91,10 @@
 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;

@@ -143,11 +142,10 @@
         .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 *);
 

@@ -1359,17 +1357,10 @@
     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)