espressif:ESP32-S3: Fix multiboot APP CPU start

Add missing function for starting the APP CPU when booting the
second image (multi image).

Signed-off-by: Almir Okato <almir.okato@espressif.com>
diff --git a/boot/espressif/hal/include/esp32s3/esp32s3.cmake b/boot/espressif/hal/include/esp32s3/esp32s3.cmake
index d8542e2..f3241ef 100644
--- a/boot/espressif/hal/include/esp32s3/esp32s3.cmake
+++ b/boot/espressif/hal/include/esp32s3/esp32s3.cmake
@@ -6,6 +6,12 @@
     ${esp_idf_dir}/components/efuse/src/esp_efuse_api_key_esp32xx.c
 )
 
+if (DEFINED CONFIG_ESP_MULTI_PROCESSOR_BOOT)
+    list(APPEND hal_srcs
+        ${src_dir}/${MCUBOOT_TARGET}/app_cpu_start.c
+        )
+endif()
+
 list(APPEND LINKER_SCRIPTS
     -T${esp_idf_dir}/components/esp_rom/${MCUBOOT_TARGET}/ld/${MCUBOOT_TARGET}.rom.newlib.ld
     )