Fix logic to allow at least one PKCS version enabled
diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index 8c0c689..d31555d 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -362,7 +362,7 @@
#error "MBEDTLS_RSA_C defined, but not all prerequisites"
#endif
-#if defined(MBEDTLS_RSA_C) && ( !defined(MBEDTLS_PKCS1_V21) || \
+#if defined(MBEDTLS_RSA_C) && ( !defined(MBEDTLS_PKCS1_V21) && \
!defined(MBEDTLS_PKCS1_V15) )
#error "MBEDTLS_RSA_C defined, but none of the PKCS1 versions enabled"
#endif