feat: sync current parallel NAND implementation from templates

include/parallel_nand_port.h

@@ -19,6 +19,8 @@ typedef struct {
     int  (*is_ready)(void);
     void (*set_write_protect)(int enabled);
     void (*delay_us)(unsigned long us);
+    /* Nonzero only when set_write_protect(0) physically releases WP#. */
+    int write_supported;
 } parallel_nand_port_t;
 
 #ifdef __cplusplus