Merge branch 'feature/relink_phy_ets_printf' into 'master'

phy: relink ets_printf of libphy.a to phy_printf

See merge request sdk/ESP8266_RTOS_SDK!1095

components/esp8266/source/phy_init.c

@@ -363,4 +363,12 @@ void esp_wifi_set_max_tx_power_via_vdd33(uint16_t vdd33)
 {
     extern void phy_vdd33_set_tpw(uint16_t vdd33);
     phy_vdd33_set_tpw(vdd33);
-}
+}
+
+/**
+ * @brief Just for compiling
+ */
+int phy_printf(const char *fmt, ...)
+{
+    return 0;
+}