rtc: ds1307: Sort the headers

It is always a good practice to keep the #includes sorted

Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>