PCI/DPC: Rename struct dpc_dev.rp to rp_extensions
"rp" is ambiguous: it might mean "this DPC device is a Root Port." But in
fact, it means "this DPC device is a Root Port *and* it supports a set of
DPC Extensions."
Rename "rp" to "rp_extensions" to make this more clear. No functional
change intended.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Keith Busch <keith.busch@intel.com> Reviewed-by: Sinan Kaya <okaya@codeaurora.org>