Remove mbedtls_param_failed from programs

All sample and test programs had a definition of mbedtls_param_failed.
This was necessary because we wanted to be able to build them in a
configuration with MBEDTLS_CHECK_PARAMS set but without a definition
of MBEDTLS_PARAM_FAILED. Now that we activate the sample definition of
MBEDTLS_PARAM_FAILED in config.h when testing with
MBEDTLS_CHECK_PARAMS set, this boilerplate code is no longer needed.

programs/ssl/ssl_server2.c

@@ -476,7 +476,6 @@ int main( void )
     "                                is printed if it is defined\n"     \
     " acceptable ciphersuite names:\n"
 
-
 #define ALPN_LIST_SIZE  10
 #define CURVE_LIST_SIZE 20
 
@@ -492,17 +491,6 @@ int main( void )
     (out_be)[(i) + 7] = (unsigned char)( ( (in_le) >> 0  ) & 0xFF );    \
 }
 
-#if defined(MBEDTLS_CHECK_PARAMS)
-#include "mbedtls/platform_util.h"
-void mbedtls_param_failed( const char *failure_condition,
-                           const char *file,
-                           int line )
-{
-    mbedtls_printf( "%s:%i: Input param failed - %s\n",
-                    file, line, failure_condition );
-    mbedtls_exit( MBEDTLS_EXIT_FAILURE );
-}
-#endif
 
 /*
  * global options