1845 allow disable of UNMAP via stmfadm(1M).

*** 65,74 ****
--- 65,76 ----
          char        rev[4];
          boolean_t   writeProtectEnableValid;
          boolean_t   writeProtectEnable;
          boolean_t   writebackCacheDisableValid;
          boolean_t   writebackCacheDisable;
+         boolean_t   unmapValid;
+         boolean_t   unmap;
          uint16_t    accessState;
          uint32_t    hostId;
          boolean_t   hostIdValid;
  } diskResource;