MAINTAINERS: Add myself as maintainer for LM95234 and TMP401 drivers

I wrote the LM95234 driver and extended the TMP401 driver substantially,
and I have hardware to test both, so it makes sense to explicitly
maintain them.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Jean Delvare <khali@linux-fr.org>