misc: ad525x_dpot: Prefer 'unsigned int' to bare use of 'unsigned'

Resolved all the Prefer 'unsigned int' to bare use of 'unsigned'
checkpatch warnings. Issue found by checkpatch.

Signed-off-by: Dhaval Shah <dhaval.shah@softnautics.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>