mfd: at91-usart: Constify at91_usart_spi_subdev and at91_usart_serial_subdev

They are never get changed, make them constant.
While at it, fix indent as well.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
1 file changed