crypto: n2 - Set err to EINVAL if snprintf fails for hmac

Return EINVAL if the snprintf check fails when constructing the
algorithm names.

Fixes: 8c20982c ("crypto: n2 - Silence gcc format-truncation false positive warnings")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202409090726.TP0WfY7p-lkp@intel.com/


Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>