PCI: allow quirks to be compiled out

This patch adds the CONFIG_PCI_QUIRKS option which allows to remove all
the PCI quirks, which are not necessarily used on embedded systems when
PCI is working properly. As this is a size-reduction option, it depends
on CONFIG_EMBEDDED. It allows to save almost 12 kilobytes of kernel
code:

   text	   data	    bss	    dec	    hex	filename
1287806	 123596	 212992	1624394	 18c94a	vmlinux.old
1275854	 123596	 212992	1612442	 189a9a	vmlinux
 -11952       0       0  -11952   -2EB0 +/-

This patch has originally been written by Zwane Mwaikambo
<zwane@arm.linux.org.uk> and is part of the Linux Tiny project.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

init/Kconfig

@@ -737,6 +737,14 @@ config VM_EVENT_COUNTERS
 	  on EMBEDDED systems.  /proc/vmstat will only show page counts
 	  if VM event counters are disabled.
 
+config PCI_QUIRKS
+	default y
+	bool "Enable PCI quirk workarounds" if EMBEDDED && PCI
+	help
+	  This enables workarounds for various PCI chipset
+          bugs/quirks. Disable this only if your target machine is
+          unaffected by PCI quirks.
+
 config SLUB_DEBUG
 	default y
 	bool "Enable SLUB debugging support" if EMBEDDED