parport: parport_serial: Use dev_get_drvdata

Instead of using to_pci_dev + pci_get_drvdata,
use dev_get_drvdata to make code simpler.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Link: https://lore.kernel.org/r/20190801191408.10977-3-sudipm.mukherjee@gmail.com


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