Staging: hv: fix smp problems in the hyperv core code

This fixes a number of SMP problems that were in the hyperv core code.

Patch originally written by K. Y. Srinivasan <ksrinivasan@novell.com>
but forward ported to the latest in-kernel code and tweaked slightly by
me.

Novell, Inc. hereby disclaims all copyright in any derivative work
copyright associated with this patch.

Signed-off-by: K. Y. Srinivasan <ksrinivasan@novell.com>
Cc: Hank Janssen <hjanssen@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>.
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>