mtd: mtdswap: use MTDSWAP_ECNT_MIN/MAX

Since macros MTDSWAP_ECNT_MIN() and MTDSWAP_ECNT_MAX() have been
defined in mtdswap.c, use them instead of open-coding.
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Acked-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/mtdswap.c

@@ -1235,10 +1235,8 @@ static int mtdswap_show(struct seq_file *s, void *data)
 
 		if (root->rb_node) {
 			count[i] = d->trees[i].count;
-			min[i] = rb_entry(rb_first(root), struct swap_eb,
-					rb)->erase_count;
-			max[i] = rb_entry(rb_last(root), struct swap_eb,
-					rb)->erase_count;
+			min[i] = MTDSWAP_ECNT_MIN(root);
+			max[i] = MTDSWAP_ECNT_MAX(root);
 		} else
 			count[i] = 0;
 	}