powerpc/PCI: include pci.h in powerpc MSI implementation

This file uses PCI MSI defines and so needs pci.h.
Tested-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

arch/powerpc/kernel/msi.c

@@ -9,6 +9,7 @@
 
 #include <linux/kernel.h>
 #include <linux/msi.h>
+#include <linux/pci.h>
 
 #include <asm/machdep.h>