Support for T-Echo Lite, credits to @Szetya for doing all the heavy lifting! (#7636)

* Support for T-Echo Lite, credts to @Szetya for doing all the heavy lifting!
* move define to ini file

variants/nrf52840/t-echo-lite/variant.cpp

@@ -0,0 +1,44 @@
+/*
+  Copyright (c) 2014-2015 Arduino LLC.  All right reserved.
+  Copyright (c) 2016 Sandeep Mistry All right reserved.
+  Copyright (c) 2018, Adafruit Industries (adafruit.com)
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the GNU Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#include "variant.h"
+#include "nrf.h"
+#include "wiring_constants.h"
+#include "wiring_digital.h"
+
+const uint32_t g_ADigitalPinMap[] = {
+    // P0 - pins 0 and 1 are hardwired for xtal and should never be enabled
+    0xff, 0xff, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+
+    // P1
+    32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47};
+
+void initVariant()
+{
+    // LED1 & LED2
+    pinMode(PIN_LED1, OUTPUT);
+    ledOff(PIN_LED1);
+
+    pinMode(PIN_LED2, OUTPUT);
+    ledOff(PIN_LED2);
+
+    pinMode(PIN_LED3, OUTPUT);
+    ledOff(PIN_LED3);
+}