espressif: Add warning for unsupported chip revision

Added checking and warning for ESP32, ESP32-S2, ESP32-C3, ESP32-S3
unsupported chip revisions on their initialization.

Made respectively changes for build system and documentation.

Signed-off-by: Almir Okato <almir.okato@espressif.com>
diff --git a/boot/espressif/tools/utils.cmake b/boot/espressif/tools/utils.cmake
new file mode 100644
index 0000000..8e3b0c2
--- /dev/null
+++ b/boot/espressif/tools/utils.cmake
@@ -0,0 +1,31 @@
+# SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+#
+# SPDX-License-Identifier: Apache-2.0
+
+# Parse config files (.conf, format: <CONFIG_NAME>=<VALUE>) and set each as
+# definitions and variables
+function(parse_and_set_config_file CONFIG_FILE)
+    file(STRINGS ${CONFIG_FILE} BOOTLOADER_CONF)
+    foreach(config ${BOOTLOADER_CONF})
+        if (NOT (${config} MATCHES "#"))
+            string(REGEX REPLACE "^[ ]+" "" config ${config})
+            string(REGEX MATCH "^[^=]+" CONFIG_NAME ${config})
+            string(REPLACE "${CONFIG_NAME}=" "" CONFIG_VALUE ${config})
+            # Overrides if already defined (definitions from latter file prevails over the former)
+            if (DEFINED ${CONFIG_NAME})
+                set(CONFIG_OLD "${CONFIG_NAME}")
+                remove_definitions(-D${CONFIG_NAME}=${${CONFIG_OLD}})
+            endif()
+            if (NOT ("${CONFIG_VALUE}" STREQUAL "n"
+                OR "${CONFIG_VALUE}" STREQUAL "N"))
+
+                if (("${CONFIG_VALUE}" STREQUAL "y")
+                    OR ("${CONFIG_VALUE}" STREQUAL "Y"))
+                    set(CONFIG_VALUE 1)
+                endif()
+                add_definitions(-D${CONFIG_NAME}=${CONFIG_VALUE})
+                set(${CONFIG_NAME} ${CONFIG_VALUE} PARENT_SCOPE)
+            endif()
+        endif()
+    endforeach()
+endfunction()