misc: ad525x_dpot: Remove unnecessary MODULE_ALIAS()

The driver has a I2C device id table that is used to create the module
aliases and also "ad_dpot" isn't a supported I2C id, so it's never used.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>