drivers: w1: Add driver for Maxim DS2484 Single-Channel 1-Wire Master

This adds a driver for Maxims DS2484 Single-Channel 1-Wire master
driver. The DS2484 features an extra pin to enable sleep modes which
is available if the pin is configured in the device tree.

Signed-off-by: Caspar Friedrich <c.s.w.friedrich@gmail.com>