x/crypto/ocsp: correct OID for DSA-with-SHA-256.

This was incorrect in crypto/x509 and go copied here.
See https://go-review.googlesource.com/#/c/20549 for the fix to
crypto/x509.

Fixes golang/go#14663.

Change-Id: I1fdca4b3f3edfeef1ee4ae01b1cf252ad8471163
Reviewed-on: https://go-review.googlesource.com/20550
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
1 file changed