PCI: Apply CONFIG_PCI_DEBUG to entire drivers/pci hierarchy

CONFIG_PCI_DEBUG=y adds -DDEBUG to CFLAGS, which enables things like
pr_debug() and dev_dbg() (and hence pci_dbg()). Previously we added
-DDEBUG for files in drivers/pci/, but not files in subdirectories of
drivers/pci/.

Add -DDEBUG to CFLAGS for all files below drivers/pci/ so CONFIG_PCI_DEBUG
applies to the entire hierarchy.

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Junhao He <[e-mail]>
Signed-off-by: Yicong Yang <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>
Reviewed-by: Krzysztof Wilczyński <[e-mail]>

drivers/pci/Makefile

···
 obj-y				+= controller/
 obj-y				+= switch/
 
-ccflags-$(CONFIG_PCI_DEBUG) := -DDEBUG
+subdir-ccflags-$(CONFIG_PCI_DEBUG) := -DDEBUG