staging: mt7621-pci: remove two register writes

There is no need to write IO and memory space window Host PCI bridge
registers before doing anything else. Just use its default values which
should be ok.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>