mbedtls: enable NIST curves optimisation.

luci using ustream-mbedtls is extremely slow vs ustream-polarssl.
polarssl alias mbedtls v1 is configured to use NIST prime speed
optimisation, so no longer disable the default optimisation for
mbedtls v2.

Compile & run tested: Archer C7v2

Signed-off-by: Kevin Darbyshire-Bryant <kevin@darbyshire-bryant.me.uk>
[Jo-Philipp Wich: refresh patch to use common format]
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

package/libs/mbedtls/patches/200-config.patch

@@ -36,15 +36,6 @@
  #define MBEDTLS_ECP_DP_SECP256K1_ENABLED
  #define MBEDTLS_ECP_DP_BP256R1_ENABLED
  #define MBEDTLS_ECP_DP_BP384R1_ENABLED
-@@ -457,7 +457,7 @@
-  *
-  * Comment this macro to disable NIST curves optimisation.
-  */
--#define MBEDTLS_ECP_NIST_OPTIM
-+//#define MBEDTLS_ECP_NIST_OPTIM
- 
- /**
-  * \def MBEDTLS_ECDSA_DETERMINISTIC
 @@ -517,7 +517,7 @@
   *      MBEDTLS_TLS_DHE_PSK_WITH_3DES_EDE_CBC_SHA
   *      MBEDTLS_TLS_DHE_PSK_WITH_RC4_128_SHA