tests: drivers: display: Add support for Smartbond Pro DevKit.

Add Kconfig option to enable allocating test buffer(s) to external
SRAM. Note that the linker section name is retrieved from the
sram-ext alias which should be compatible to zephyr,memory-region.

Signed-off-by: Ioannis Karachalios <ioannis.karachalios.px@renesas.com>

tests/drivers/display/display_read_write/Kconfig

@@ -0,0 +1,10 @@
+# Copyright (c) 2023 Renesas Electronics Corporation
+# SPDX-License-Identifier: Apache-2.0
+
+mainmenu "Display Read/Write Test"
+
+source "Kconfig.zephyr"
+
+config DISPLAY_READ_WRITE_BUF_SRAM_EXT
+	bool "Buffer allocation is done from sram-ext alias"
+	default n

tests/drivers/display/display_read_write/src/main.c

@@ -8,14 +8,22 @@
 #include <zephyr/ztest.h>
 #include <zephyr/device.h>
 #include <zephyr/logging/log.h>
+#include <zephyr/linker/devicetree_regions.h>
 
 LOG_MODULE_DECLARE(display_api, CONFIG_DISPLAY_LOG_LEVEL);
 
+#if CONFIG_DISPLAY_READ_WRITE_BUF_SRAM_EXT
+#define DISP_BUFFER_LINKER_SECTION	\
+	Z_GENERIC_SECTION(LINKER_DT_NODE_REGION_NAME(DT_ALIAS(sram_ext)))
+#else
+#define DISP_BUFFER_LINKER_SECTION
+#endif
+
 static const struct device *dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_display));
 static const uint32_t display_width = DT_PROP(DT_CHOSEN(zephyr_display), width);
 static const uint32_t display_height = DT_PROP(DT_CHOSEN(zephyr_display), height);
 static uint8_t disp_buffer[DT_PROP(DT_CHOSEN(zephyr_display), width) *
-			   DT_PROP(DT_CHOSEN(zephyr_display), height) * 4];
+	DT_PROP(DT_CHOSEN(zephyr_display), height) * 4] DISP_BUFFER_LINKER_SECTION;
 static struct display_capabilities cfg;
 static uint8_t bpp;
 static bool is_tiled;