Both chips are quite similar to other chips of this series, so add
support for them to the lm90 driver. Also mention ON Semiconductor NCT210,
which is pin and register compatible to ADM1021A.

None of the chips support the secondary manufacturer and chip ID registers
at 0x3e and 0x3f, but return 0 when reading from those registers.
Use that information to improve the accuracy of chip detection code.

Devicetree nodes are not added for the added chips since it is quite
unlikely that such old chips will ever be used in a devicetree based
system. They can be added later if needed.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>