Use 1024-bit ESA key in PKCS#11 tests

This avoids an in-your-face warning about small key sizes with SoftHSM 2.0.
diff --git a/tests/suites/test_suite_pkcs11_client.function b/tests/suites/test_suite_pkcs11_client.function
index 9c16a35..34800ef 100644
--- a/tests/suites/test_suite_pkcs11_client.function
+++ b/tests/suites/test_suite_pkcs11_client.function
@@ -27,7 +27,7 @@
         }                                                               \
     } while( 0 )
 
-#define RSA_KEY_SIZE_BITS 512
+#define RSA_KEY_SIZE_BITS 1024
 #define RSA_KEY_SIZE_BYTES ( ( RSA_KEY_SIZE_BITS + 7 ) / 8 )
 #define ECP_GROUP_ID MBEDTLS_ECP_DP_SECP256R1
 #define ECP_GROUP_NAME( id ) #id