misc: hpilo: rename device creation loop variable

In `ilo_probe()`, the loop variable `minor` isn't really the minor
device number, it's the channel or slot number.  Rename it to `slot` for
consistency.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20240119132032.106053-3-abbotti@mev.co.uk


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>