Merge pull request #14263 from mikaleppanen/5_15_wisun_mac_addr_get_corr

[mbed-os-5.15] Added missing const qualifier to mesh ethernet mac addr get

Author: 0xc0170

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

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

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

@@ -130,7 +130,7 @@ 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;