Initial sysparam implementation

Problems with inability to write individual bytes to flash.  Need to reorganize
to read/write word-multiples instead.

core/include/esp/types.h

@@ -3,6 +3,7 @@
 
 #include <stdint.h>
 #include <stdbool.h>
+#include <stddef.h>
 
 typedef volatile uint32_t *esp_reg_t;