lmsensors: fix fancontrol init script

Make the 'fancontrol stop' command work again by using the fancontrol
pid file instead of matching the process by name. While at it, also do
a bit of cleaning.

Signed-off-by: Marc Ferland <ferlandm@sonatest.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>