spiram: add header guards to esp32s3/spiram.h and remove the exception

components/esp32s3/include/esp32s3/spiram.h

@@ -21,6 +21,10 @@
 #include <stdbool.h>
 #include "esp_err.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /**
  * @brief Initialize spiram interface/hardware. Normally called from cpu_start.c.
  *
@@ -135,4 +139,8 @@ uint32_t rodata_flash_end_page_get(void);
 int rodata_flash2spiram_offset(void);
 #endif
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif