net: wwan: iosm: Switch to use module_pci_driver() macro

Eliminate some boilerplate code by using module_pci_driver() instead of
init/exit, moving the salient bits from init into probe.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>