mtd: ubi: remove redundant check on bytes_left at end of function

In function ubi_nvmem_reg_read the while-loop can only be exiting
of bytes_left is zero or an error has occurred. There is an exit
return path if an error occurs, so the bytes_left can only be
zero after that point. Hence the check for a non-zero bytes_left
at the end of the function is redundant and can be removed. Remove
the check and just return 0.

Signed-off-by: Colin Ian King <[e-mail]>
Reviewed-by: Zhihao Cheng <[e-mail]>
Signed-off-by: Richard Weinberger <[e-mail]>

drivers/mtd/ubi/nvmem.c

···
 	if (err)
 		return err;
 
-	return bytes_left == 0 ? 0 : -EIO;
+	return 0;
 }
 
 static int ubi_nvmem_add(struct ubi_volume_info *vi)