max6875: Discard obsolete detect method

There is no point in implementing a detect callback for the MAX6875, as
this device can't be detected. It was there solely to handle "force"
module parameters to instantiate devices, but now we have a better sysfs
interface that can do the same.

So we can get rid of the ugly module parameters and the detect callback.
This basically divides the binary module size by 2.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Ben Gardner <gardner.ben@gmail.com>