Revert "xen/pv-on-hvm kexec: add xs_reset_watches to shutdown watches from old kernel"

This reverts commit ddacf5ef684a655abe2bb50c4b2a5b72ae0d5e05.
As when booting the kernel under Amazon EC2 as an HVM guest it ends up
hanging during startup. Reverting this we loose the fix for kexec
booting to the crash kernels.

Fixes Canonical BZ #901305 (http://bugs.launchpad.net/bugs/901305)

Tested-by: Alessandro Salvatori <[e-mail]>
Reported-by: Stefan Bader <[e-mail]>
Acked-by: Ian Campbell <[e-mail]>
Signed-off-by: Konrad Rzeszutek Wilk <[e-mail]>

drivers/xen/xenbus/xenbus_xs.c

···
 	return NULL;
 }
 
-static void xs_reset_watches(void)
-{
-	int err;
-
-	err = xs_error(xs_single(XBT_NIL, XS_RESET_WATCHES, "", NULL));
-	if (err && err != -EEXIST)
-		printk(KERN_WARNING "xs_reset_watches failed: %d\n", err);
-}
-
 /* Register callback to watch this node. */
 int register_xenbus_watch(struct xenbus_watch *watch)
 {
···
 	task = kthread_run(xenbus_thread, NULL, "xenbus");
 	if (IS_ERR(task))
 		return PTR_ERR(task);
-
-	/* shutdown watches for kexec boot */
-	if (xen_hvm_domain())
-		xs_reset_watches();
 
 	return 0;
 }

include/xen/interface/io/xs_wire.h

···
     XS_IS_DOMAIN_INTRODUCED,
     XS_RESUME,
     XS_SET_TARGET,
-    XS_RESTRICT,
-    XS_RESET_WATCHES
+    XS_RESTRICT
 };
 
 #define XS_WRITE_NONE "NONE"