scsi: fix incorrect return value of read when reading from cookie

lib/link/seven/scsi.c

@@ -96,8 +96,7 @@ CASIO_LOCAL ssize_t seven_scsi_read(seven_scsi_cookie_t *cookie,
 			memcpy(buffer, cookie->ptr, size);
 			cookie->ptr += size;
 			cookie->left -= size;
-			copiedsize += cookie->left;
-			return copiedsize;
+			return size;
 		}
 
 		memcpy(buffer, cookie->ptr, cookie->left);