PCI/DPC: Rename from pcie-dpc.c to dpc.c

Rename pcie-dpc.c to dpc.c.  The path "drivers/pci/pcie/pcie-dpc.c" has
more occurrences of "pci" than necessary.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

drivers/pci/pcie/Makefile

@@ -15,5 +15,5 @@ obj-$(CONFIG_PCIEAER)		+= aer/
 
 obj-$(CONFIG_PCIE_PME) += pme.o
 
-obj-$(CONFIG_PCIE_DPC) += pcie-dpc.o
+obj-$(CONFIG_PCIE_DPC) += dpc.o
 obj-$(CONFIG_PCIE_PTM) += ptm.o