xen-pcifront: Remove duplicate inclusion of headers.

In drivers/pci/xen-pcifront.c the xen/xenbus.h header is included twice -
once is enough.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/pci/xen-pcifront.c

@@ -13,7 +13,6 @@
 #include <linux/spinlock.h>
 #include <linux/pci.h>
 #include <linux/msi.h>
-#include <xen/xenbus.h>
 #include <xen/interface/io/pciif.h>
 #include <asm/xen/pci.h>
 #include <linux/interrupt.h>