Suppress an error when doing SM2 sign/verify ops

This was fixed in #8321 right after the 1.1.1 was released but never
back ported to 1.1.1. Now fix it.

Issue reported from lua-openssl project.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10278)

crypto/sm2/sm2_pmeth.c

@@ -220,6 +220,10 @@ static int pkey_sm2_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
         *(size_t *)p2 = smctx->id_len;
         return 1;
 
+    case EVP_PKEY_CTRL_DIGESTINIT:
+        /* nothing to be inited, this is to suppress the error... */
+        return 1;
+
     default:
         return -2;
     }