hwmon: (lm93) Convert to a new-style i2c driver

The new-style lm93 driver implements the optional detect() callback
to cover the use cases of the legacy driver.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Mark M. Hoffman <mhoffman@lightlink.com>
Cc: Eric J. Bowersox <ericb@aspsys.com>
Cc: Carsten Emde <cbe@osadl.org>
Cc: Hans J. Koch <hjk@linutronix.de>