Removed erroneous zfs_inode_destroy() calls from zfs_rmnode().

iput_final() already calls zpl_inode_destroy() -> zfs_inode_destroy()
for us after zfs_zinactive(), thus making sure that the inode is
properly cleaned up.

The zfs_inode_destroy() calls in zfs_rmnode() would lead to a
double-free.

Fixes openzfs#282

module/zfs/zfs_dir.c

@@ -614,7 +614,6 @@ zfs_rmnode(znode_t *zp)
 			 * Leave it in the unlinked set.
 			 */
 			zfs_znode_dmu_fini(zp);
-			zfs_inode_destroy(ZTOI(zp));
 
 			return;
 		}
@@ -629,7 +628,6 @@ zfs_rmnode(znode_t *zp)
 		 * Not enough space.  Leave the file in the unlinked set.
 		 */
 		zfs_znode_dmu_fini(zp);
-		zfs_inode_destroy(ZTOI(zp));
 		return;
 	}
 
@@ -669,7 +667,6 @@ zfs_rmnode(znode_t *zp)
 		 */
 		dmu_tx_abort(tx);
 		zfs_znode_dmu_fini(zp);
-		zfs_inode_destroy(ZTOI(zp));
 		goto out;
 	}