hwmon/smsc47m192: Document the LPC47M292 as supported

The new SMSC LPC47M292 Super-I/O chip includes a hardware monitoring
block which is compatible with those of the LPC47M192.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Hartmut Rick <linux@rick.claranet.de>