w1: ds2760: add support for EEPROM read and write

In order to modify the DS2762's status registers and to add support for
sleep mode, there is need for functions to write the internal EEPROM.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Acked-by: Matt Reimer <mreimer@vpop.net>
Acked-by: Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>