Introduce CONFIG_XEN_PVHVM compile option

This patch introduce a CONFIG_XEN_PVHVM compile time option to
enable/disable Xen PV on HVM support.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

drivers/xen/Kconfig

@@ -64,7 +64,7 @@ config XEN_SYS_HYPERVISOR
 
 config XEN_PLATFORM_PCI
 	tristate "xen platform pci device driver"
-	depends on XEN
+	depends on XEN_PVHVM
 	default m
 	help
 	  Driver for the Xen PCI Platform device: it is responsible for