hwmon: (adm1026) More cleanups (updated)

Various cleanups:
* Drop an unused define.
* Drop unused struct member "type".
* Drop one useless instruction.
* Drop redundant initializations to 0.
* Rename new_client to client.
* Drop a useless cast.
* Minor code cleanup.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>