selftests/bpf: Update test_tag to use sha256

commit 603b44162325 ("bpf: Update the bpf_prog_calc_tag to use SHA256")
changed digest of prog_tag to SHA256 but forgot to update tests
correspondingly. Fix it.

Fixes: 603b44162325 ("bpf: Update the bpf_prog_calc_tag to use SHA256")
Signed-off-by: Xing Guo <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexei Starovoitov <[e-mail]>

tools/testing/selftests/bpf/test_tag.c

···
 	static const struct sockaddr_alg alg = {
 		.salg_family	= AF_ALG,
 		.salg_type	= "hash",
-		.salg_name	= "sha1",
+		.salg_name	= "sha256",
 	};
 	int fd_base, fd_alg, ret;
 	ssize_t size;