Drivers: hv: vmbus: Remove the undesired put_cpu_ptr() in hv_synic_cleanup()

With CONFIG_DEBUG_PREEMPT=y, the put_cpu_ptr() triggers an underflow
warning in preempt_count_sub().

Fixes: 37cdd991 ("vmbus: put related per-cpu variable together")
Cc: stable@vger.kernel.org
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>