staging: mt7621-pci: review 'pci_host_bridge' assigned variables

staging: mt7621-pci: review 'pci_host_bridge' assigned variables

PCI kernel apis now set some variables related with pci_host_bridge
by default and it is not necessary to setup them in driver code.
Host bridge parent device is set by default to the platform device
and 'swizzle_irq' is also set to its default function. These two
are not necessary to be set here. Hence remove them.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20201123093637.8300-5-sergio.paracuellos@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>