Drivers: hv: Fix a bug in get_vp_index()

Linux' notion of cpuid is different from the Host's notion of CPUID. In the
call to bind the channel interrupts, we should use the host's notion of
CPU Ids. Fix this bug.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: Stable <stable@vger.kernel.org> (V3.9)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>