Drivers: hv: vmbus: Export the vmbus_set_event() API

In preparation for moving some ring buffer functionality out of the
vmbus driver, export the API for signaling the host.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/connection.c

@@ -495,3 +495,4 @@ void vmbus_set_event(struct vmbus_channel *channel)
 
 	hv_do_hypercall(HVCALL_SIGNAL_EVENT, channel->sig_event, NULL);
 }
+EXPORT_SYMBOL_GPL(vmbus_set_event);