onenand_spl_simple: Add a simple OneNAND read function

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
diff --git a/include/onenand_uboot.h b/include/onenand_uboot.h
index fd01040..d69e0d2 100644
--- a/include/onenand_uboot.h
+++ b/include/onenand_uboot.h
@@ -49,6 +49,7 @@
 					int boundary, int lock);
 
 /* SPL */
+int onenand_spl_read_block(int block, int offset, int len, void *dst);
 void onenand_spl_load_image(uint32_t offs, uint32_t size, void *dst);
 
 #endif /* __UBOOT_ONENAND_H */