include: dev: Modify the flash_write api to use a flag for spare bytes.

Change-Id: I90a4a5f477b17aa48a22c67f3b05595a27f53a16
diff --git a/include/dev/flash.h b/include/dev/flash.h
index 9fa10bc..6c2402d 100644
--- a/include/dev/flash.h
+++ b/include/dev/flash.h
@@ -68,7 +68,7 @@
 int flash_erase(struct ptentry *ptn);
 int flash_read_ext(struct ptentry *ptn, unsigned extra_per_page,
 		   unsigned offset, void *data, unsigned bytes);
-int flash_write(struct ptentry *ptn, unsigned extra_per_page, const void *data,
+int flash_write(struct ptentry *ptn, unsigned write_extra_bytes, const void *data,
 		unsigned bytes);
 
 static inline int flash_read(struct ptentry *ptn, unsigned offset, void *data,