soc: esp32s2: add initial soc support files for esp32s2

by adding specific soc files for esp32s2 bring-up, such as:
- linker script
- soc initialization code
- initial device tree source files
- esp32s2 saola board support.

Signed-off-by: Glauber Maroto Ferreira <glauber.ferreira@espressif.com>

soc/xtensa/esp32s2/Kconfig.soc

@@ -0,0 +1,69 @@
+# Copyright (c) 2021 Espressif Systems (Shanghai) Co., Ltd.
+# SPDX-License-Identifier: Apache-2.0
+
+config SOC_ESP32S2
+	bool "ESP32S2"
+	select XTENSA
+	select ATOMIC_OPERATIONS_C
+
+if SOC_ESP32S2
+
+config IDF_TARGET_ESP32S2
+	bool "ESP32S2 as target board"
+	default y
+
+config ESPTOOLPY_FLASHFREQ_80M
+	bool
+	default y
+
+choice
+	prompt "Instruction cache line size"
+	default ESP32S2_INSTRUCTION_CACHE_LINE_32B
+
+	config ESP32S2_INSTRUCTION_CACHE_LINE_16B
+		bool "16 Bytes"
+
+	config ESP32S2_INSTRUCTION_CACHE_LINE_32B
+		bool "32 Bytes"
+
+endchoice
+
+choice
+	prompt "Instruction cache size"
+	default ESP32S2_INSTRUCTION_CACHE_8KB
+
+	config ESP32S2_INSTRUCTION_CACHE_8KB
+		bool "8KB instruction cache size"
+
+	config ESP32S2_INSTRUCTION_CACHE_16KB
+		bool "16KB instruction cache size"
+
+endchoice
+
+choice
+	prompt "Data cache size"
+	default ESP32S2_DATA_CACHE_0KB
+
+	config ESP32S2_DATA_CACHE_0KB
+		bool "0KB data cache size"
+
+	config ESP32S2_DATA_CACHE_8KB
+		bool "8KB data cache size"
+
+	config ESP32S2_DATA_CACHE_16KB
+		bool "16KB data cache size"
+
+endchoice
+
+config ESP32S2_INSTRUCTION_CACHE_SIZE
+	hex
+	default 0x2000
+	default 0x4000 if ESP32S2_INSTRUCTION_CACHE_16KB
+
+config ESP32S2_DATA_CACHE_SIZE
+	hex
+	default 0x0000
+	default 0x2000 if ESP32S2_DATA_CACHE_8KB
+	default 0x4000 if ESP32S2_DATA_CACHE_16KB
+
+endif