ltc4215/ltc4245: Discard obsolete detect methods

There is no point in implementing a detect callback for the LTC4215
and LTC4245, as these devices 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
callbacks. This shrinks the binary module sizes by 36% and 46%,
respectively.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Ira W. Snyder <iws@ovro.caltech.edu>