Make the chip detection code more similar to the one used for the
same chips in watchdog/w83627hf_wdt.c and hwmon/w83627ehf.c.

Apart from better maintainability we gain
- unified naming of chips (e.g. 677C -> NCT6776F)
- driver works with all revisions of the chips
  (least 4 bits of id are masked)
Signed-off-by: NHeiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>