f2fs: simplify by using a literal

We can make the code a bit simpler because we know that "!retry" is
zero.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/super.c

@@ -1133,7 +1133,7 @@ free_sbi:
 
 	/* give only one another chance */
 	if (retry) {
-		retry = !retry;
+		retry = 0;
 		shrink_dcache_sb(sb);
 		goto try_onemore;
 	}