Refactor OTA API

src/flash.h

@@ -1,9 +1,13 @@
 #include "arch.h"
+#include "ota.h"
+
+#if MG_OTA != MG_OTA_NONE && MG_OTA != MG_OTA_CUSTOM
 
 struct mg_flash {
-  void *start;   // Address at which flash starts
-  size_t size;   // Flash size
-  size_t align;  // Write alignment
+  void *start;    // Address at which flash starts
+  size_t size;    // Flash size
+  size_t secsz;   // Sector size
+  size_t align;   // Write alignment
   bool (*write_fn)(void *, const void *, size_t);  // Write function
   bool (*swap_fn)(void);                           // Swap partitions
 };
@@ -11,3 +15,5 @@ struct mg_flash {
 bool mg_ota_flash_begin(size_t new_firmware_size, struct mg_flash *flash);
 bool mg_ota_flash_write(const void *buf, size_t len, struct mg_flash *flash);
 bool mg_ota_flash_end(struct mg_flash *flash);
+
+#endif