lib: add GENERIC_PCI_IOMAP

Many architectures want a generic pci_iomap but
not the rest of iomap.c. Split that to a separate .c
file and add a new config symbol. select automatically
by GENERIC_IOMAP.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/include/asm-generic/iomap.h b/include/asm-generic/iomap.h
index 98dcd76..8a3d4fd 100644
--- a/include/asm-generic/iomap.h
+++ b/include/asm-generic/iomap.h
@@ -67,18 +67,15 @@
 #endif
 
 #ifdef CONFIG_PCI
-/* Create a virtual mapping cookie for a PCI BAR (memory or IO) */
+/* Destroy a virtual mapping cookie for a PCI BAR (memory or IO) */
 struct pci_dev;
-extern void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max);
 extern void pci_iounmap(struct pci_dev *dev, void __iomem *);
 #else
 struct pci_dev;
-static inline void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max)
-{
-	return NULL;
-}
 static inline void pci_iounmap(struct pci_dev *dev, void __iomem *addr)
 { }
 #endif
 
+#include <asm-generic/pci_iomap.h>
+
 #endif