hwmon: (lm90) Introduce flag indicating extended temperature support

[ Upstream commit f347e249

 ]

A flag indicating extended temperature support makes it easier
to add support for additional chips with this functionality.

Cc: David T. Wilson <david.wilson@nasa.gov>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>