ioctl_ficlone02: Fill range to avoid EINVAL

To avoid ioctl(..., FICLONERANGE, ...) on filesystem which supports it
failing with EINVAL (now it succeeds as the first test, which is less
confusing).

Link: https://lore.kernel.org/ltp/ZqeFKkUbhlikEfNS@yuki/
Suggested-by: Cyril Hrubis <[email protected]>
Signed-off-by: Petr Vorel <[email protected]>

testcases/kernel/syscalls/ioctl/ioctl_ficlone02.c

@@ -43,6 +43,8 @@ static void setup(void)
 
 	SAFE_STAT(MNTPOINT, &sb);
 
+	tst_fill_file(SRCPATH, 0x00, sb.st_blksize, 1);
+
 	clone_range->src_offset = 0;
 	clone_range->src_length = sb.st_blksize;
 	clone_range->dest_offset = 0;