lspci: Reorder Express Root Complex registers to Cap, Ctl, Sta

lspci: Reorder Express Root Complex registers to Cap, Ctl, Sta

Registers in the PCI Express Capability come in sets of three (Capability,
Control, Status), and we typically print them in that order.  The Root
Complex-related registers were an exception: we printed them in the
(Control, Capability, Status) order.

Decode the RootCap, RootCtl, and RootSta registers in the usual order.

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