Remove old lguest I/O infrrasructure.

This patch gets rid of the old lguest host I/O infrastructure and
replaces it with a single hypercall "LHCALL_NOTIFY" which takes an
address.

The main change is the removal of io.c: that mainly did inter-guest
I/O, which virtio doesn't yet support.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index 41b26e5..3aec29e 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -202,13 +202,12 @@
 		if (lg->hcall)
 			do_hypercalls(lg);
 
-		/* It's possible the Guest did a SEND_DMA hypercall to the
+		/* It's possible the Guest did a NOTIFY hypercall to the
 		 * Launcher, in which case we return from the read() now. */
-		if (lg->dma_is_pending) {
-			if (put_user(lg->pending_dma, user) ||
-			    put_user(lg->pending_key, user+1))
+		if (lg->pending_notify) {
+			if (put_user(lg->pending_notify, user))
 				return -EFAULT;
-			return sizeof(unsigned long)*2;
+			return sizeof(lg->pending_notify);
 		}
 
 		/* Check for signals */
@@ -288,9 +287,6 @@
 	if (err)
 		goto unmap;
 
-	/* The I/O subsystem needs some things initialized. */
-	lguest_io_init();
-
 	/* We might need to reserve an interrupt vector. */
 	err = init_interrupts();
 	if (err)