boards: arm: 96b_wistrio: Add 3.3v Low speed connector support

Add support for 3.3v Low speed connector available on the Wistrio
board inorder to access peripherals in a board independent way.

Following peripherals are supported:

1. 7-GPIOs
2. I2C0
3. UART0

Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>

boards/arm/96b_wistrio/96b_lscon.dtsi

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2019 Linaro Ltd.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	lscon_96b: connector {
+		compatible = "96b-lscon-3v3";
+		#gpio-cells = <2>;
+		gpio-map-mask = <0xffffffff 0xffffffc0>;
+		gpio-map-pass-thru = <0 0x3f>;
+		gpio-map = <13 0 &gpioa 8 0>,	/* GPIO-A */
+			   <14 0 &gpiob 3 0>,	/* GPIO-B */
+			   /* GPIO-C not connected */
+			   <16 0 &gpiob 5 0>,	/* GPIO-D */
+			   <17 0 &gpioa 13 0>,	/* GPIO-E */
+			   <18 0 &gpioa 14 0>,	/* GPIO-F */
+			   <19 0 &gpioa 12 0>,	/* GPIO-G */
+			   <20 0 &gpiob 4 0>;	/* GPIO-H */
+	};
+};
+
+lscon_96b_i2c0: &i2c1 {};
+lscon_96b_uart0: &usart1 {};

boards/arm/96b_wistrio/96b_wistrio.dts

@@ -6,6 +6,7 @@
 
 /dts-v1/;
 #include <st/l1/stm32l151Xb-a.dtsi>
+#include "96b_lscon.dtsi"
 
 / {
 	model = "RAKWireless 96boards WisTrio board";

boards/arm/96b_wistrio/doc/96b_wistrio.rst

@@ -19,7 +19,7 @@ boards.
 
      96Boards WisTrio
 
-This board is one of the 96Boards IoT Edition platform providing LoRa
+This board is one of the `96Boards IoT Edition`_ platforms providing LoRa
 connectivity.
 
 Hardware
@@ -212,3 +212,6 @@ References
 
 .. _Getting started page:
    https://github.com/blacksphere/blackmagic/wiki/Getting-Started
+
+.. _96Boards IoT Edition:
+    https://linaro.co/ie-specification