PCI: iproc: Do not reset PAXC when initializing the driver

During initialization, the current iProc PCIe host driver resets PAXC and
the downstream internal endpoint device that PAXC connects to.  If the
endpoint device is already loaded with firmware and has started running
from the bootloader stage, this downstream reset causes the endpoint device
to stop working.

Signed-off-by: Ray Jui <raj.jui@broadcom.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Scott Branden <scott.branden@broadcom.com>