Drivers: hv: vmbus: Fix crash handler reset of Hyper-V synic

The crash handler calls hv_synic_cleanup() to shutdown the
Hyper-V synthetic interrupt controller.  But if the CPU
that calls hv_synic_cleanup() has a VMbus channel interrupt
assigned to it (which is likely the case in smaller VM sizes),
hv_synic_cleanup() returns an error and the synthetic
interrupt controller isn't shutdown.  While the lack of
being shutdown hasn't caused a known problem, it still
should be fixed for highest reliability.

So directly call hv_synic_disable_regs() instead of
hv_synic_cleanup(), which ensures that the synic is always
shutdown.
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/hv/vmbus_drv.c

@@ -2310,7 +2310,7 @@ static void hv_crash_handler(struct pt_regs *regs)
 	vmbus_connection.conn_state = DISCONNECTED;
 	cpu = smp_processor_id();
 	hv_stimer_cleanup(cpu);
-	hv_synic_cleanup(cpu);
+	hv_synic_disable_regs(cpu);
 	hyperv_cleanup();
 };