hwmon/w83627ehf: Convert to a platform driver

Remove i2c-isa from the w83627ehf driver, and use a platform driver
instead.

Signed-off-by: David Hubbard <david.c.hubbard@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>