Drivers: hv: vmbus: Remove unnecessary channel->lock critical sections (sc_list updaters)

None of the readers/updaters of sc_list rely on channel->lock for
synchronization.

Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20200617164642.37393-7-parri.andrea@gmail.com


Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>