Fix a lock in provider_remove_store_methods()

We were taking a read lock. It should have been a write lock.

Fixes #19474

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from #19481)

(cherry picked from commit 6962e21)

crypto/provider_core.c

@@ -1204,7 +1204,7 @@ static int provider_remove_store_methods(OSSL_PROVIDER *prov)
     if (!freeing) {
         int acc;
 
-        if (!CRYPTO_THREAD_read_lock(prov->opbits_lock))
+        if (!CRYPTO_THREAD_write_lock(prov->opbits_lock))
             return 0;
         OPENSSL_free(prov->operation_bits);
         prov->operation_bits = NULL;