drivers:hv: Export the API to invoke a hypercall on Hyper-V

This patch exposes the function that hv_vmbus.ko uses to make hypercalls.  This
is necessary for retargeting an interrupt when it is given a new affinity.

Since we are exporting this API, rename the API as it will be visible outside
the hv.c file.

Signed-off-by: Jake Oshins <jakeo@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 12156db..9beeb14 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -587,7 +587,7 @@
 			 enum hv_message_type message_type,
 			 void *payload, size_t payload_size);
 
-extern u16 hv_signal_event(void *con_id);
+extern int hv_signal_event(void *con_id);
 
 extern int hv_synic_alloc(void);