Revert "zpool reopen should detect expanded devices"

This reverts commit 2a16d4cfaf.

The commit was causing a "attempt to access beyond the end
of device" error:

list.zfsonlinux.org/pipermail/zfs-discuss/2018-September/032217.html

lib/libefi/rdwr_efi.c

@@ -22,7 +22,6 @@
 /*
  * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright 2012 Nexenta Systems, Inc.  All rights reserved.
- * Copyright (c) 2018 by Delphix. All rights reserved.
  */
 
 #include <stdio.h>
@@ -1154,7 +1153,7 @@ efi_use_whole_disk(int fd)
 
 	/*
 	 * Find the last physically non-zero partition.
-	 * This should be the reserved partition.
+	 * This is the reserved partition.
 	 */
 	for (i = 0; i < efi_label->efi_nparts; i ++) {
 		if (resv_start < efi_label->efi_parts[i].p_start) {
@@ -1163,23 +1162,6 @@ efi_use_whole_disk(int fd)
 		}
 	}
 
-	/*
-	 * Verify that we've found the reserved partition by checking
-	 * that it looks the way it did when we created it in zpool_label_disk.
-	 * If we've found the incorrect partition, then we know that this
-	 * device was reformatted and no longer is soley used by ZFS.
-	 */
-	if ((efi_label->efi_parts[resv_index].p_size != EFI_MIN_RESV_SIZE) ||
-	    (efi_label->efi_parts[resv_index].p_tag != V_RESERVED) ||
-	    (resv_index != 8)) {
-		if (efi_debug) {
-			(void) fprintf(stderr,
-			    "efi_use_whole_disk: wholedisk not available\n");
-		}
-		efi_free(efi_label);
-		return (VT_ENOSPC);
-	}
-
 	/*
 	 * Find the last physically non-zero partition before that.
 	 * This is the data partition.