Drivers: hv: vmbus: Use the vp_index map even for channels bound to CPU 0

Drivers: hv: vmbus: Use the vp_index map even for channels bound to CPU 0

Map target_cpu to target_vcpu using the mapping table.
We should use the mapping table to transform guest CPU ID to VP Index
as is done for the non-performance critical channels.
While the value CPU 0 is special and will
map to VP index 0, it is good to be consistent.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 9c6e64adf200d3bac0dd47d52cdbd3bd428384a5)

Orabug: 21886720
Signed-off-by: Jason Luo <zhangqing.luo@oracle.com>