PCI: altera: Simplify TLP_CFG_DW1 usage

TLP_CFG_DW1() was only used with altera->root_bus_nr and RP_DEVFN, so
encode that directly into the macro so we don't have to clutter the uses
with the TLP_REQ_ID() usage.  No functional change intended.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>