stm32/network_wiznet5k: Add ability to set the MAC address.

ports/stm32/network_wiznet5k.c

@@ -25,6 +25,8 @@
  */
 
 #include <stdio.h>
+#include <string.h>
+
 #include "py/runtime.h"
 #include "py/mphal.h"
 #include "spi.h"
@@ -398,6 +400,16 @@ STATIC mp_obj_t wiznet5k_config(size_t n_args, const mp_obj_t *args, mp_map_t *k
             if (MP_MAP_SLOT_IS_FILLED(kwargs, i)) {
                 mp_map_elem_t *e = &kwargs->table[i];
                 switch (mp_obj_str_get_qstr(e->key)) {
+                    case MP_QSTR_mac: {
+                        mp_buffer_info_t buf;
+                        mp_get_buffer_raise(e->value, &buf, MP_BUFFER_READ);
+                        if (buf.len != 6) {
+                            mp_raise_ValueError(NULL);
+                        }
+                        setSHAR(buf.buf);
+                        memcpy(self->netif.hwaddr, buf.buf, 6);
+                        break;
+                    }
                     case MP_QSTR_trace: {
                         self->trace_flags = mp_obj_get_int(e->value);
                         break;