[SPARC64]: Add LDOM virtual channel driver and VIO device layer.

Virtual devices on Sun Logical Domains are built on top
of a virtual channel framework.  This, with help of hypervisor
interfaces, provides a link layer protocol with basic
handshaking over which virtual device clients and servers
communicate.

Built on top of this is a VIO device protocol which has it's
own handshaking and message types.  At this layer attributes
are exchanged (disk size, network device addresses, etc.)
descriptor rings are registered, and data transfers are
triggers and replied to.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc64/Kconfig b/arch/sparc64/Kconfig
index 6566d13..af59daa 100644
--- a/arch/sparc64/Kconfig
+++ b/arch/sparc64/Kconfig
@@ -305,6 +305,12 @@
 	bool
 	default y
 
+config SUN_LDOMS
+	bool "Sun Logical Domains support"
+	help
+	  Say Y here is you want to support virtual devices via
+	  Logical Domains.
+
 config PCI
 	bool "PCI support"
 	select ARCH_SUPPORTS_MSI