drivers: gpio: add Broadcom iProc GPIO controller driver

Add device driver, bindings and build-only test for
Broadcom iProc GPIO controller.

Signed-off-by: Yong Cong Sin <ycsin@meta.com>

tests/drivers/build_all/gpio/iproc.overlay

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2024, Meta Platforms
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Application overlay for testing iproc driver builds
+ */
+
+ / {
+	test {
+		test_int_gpio {
+			#address-cells = <1>;
+			#size-cells = <1>;
+			interrupt-parent = <&test_nvic>;
+
+			test_nvic: interrupt-controller@bbbbcccc  {
+				compatible = "arm,v6m-nvic";
+				reg = <0xbbbbcccc 0xc00>;
+				interrupt-controller;
+				#interrupt-cells = <2>;
+				arm,num-irq-priority-bits = <3>;
+			};
+
+			test_gpio_iproc: gpio@c10fee {
+				compatible = "brcm,iproc-gpio";
+				gpio-controller;
+				reg = <0xc10fee 0x4c>;
+				ngpios = <6>;
+				interrupts = <28 1>;
+				#gpio-cells = <0x2>;
+				status = "okay";
+			};
+		};
+	};
+};

tests/drivers/build_all/gpio/testcase.yaml

@@ -34,3 +34,8 @@ tests:
     extra_args:
       - DTC_OVERLAY_FILE="app.overlay;adc_ads1145s0x_gpio.overlay"
       - CONF_FILE="adc_ads1145s0x_gpio.conf"
+
+  drivers.gpio.build.iproc:
+    platform_allow: qemu_cortex_m3
+    depends_on: gpio
+    extra_args: DTC_OVERLAY_FILE="iproc.overlay"