Added missing const qualifier to mesh ethernet mac addr get

Author: Mika Leppänen

connectivity/nanostack/mbed-mesh-api/mbed-mesh-api/NanostackEthernetInterface.h

@@ -28,7 +28,7 @@ class Nanostack::EthernetInterface final : public Nanostack::Interface {
                           nsapi_ip_stack_t stack = DEFAULT_STACK,
                           bool blocking = true) override;
     nsapi_error_t bringdown() override;
-    void get_mac_address(uint8_t *buf);
+    void get_mac_address(uint8_t *buf) const override;
     char *get_mac_address(char *buf, nsapi_size_t buflen) override;
 
     char *get_interface_name(char *buf) override;

connectivity/nanostack/mbed-mesh-api/source/NanostackEthernetInterface.cpp

@@ -133,7 +133,7 @@ char *Nanostack::EthernetInterface::get_interface_name(char *buf)
     return buf;
 };
 
-void Nanostack::EthernetInterface::get_mac_address(uint8_t *buf)
+void Nanostack::EthernetInterface::get_mac_address(uint8_t *buf) const
 {
     if (!buf) {
         return;