hv: fix return type of hv_post_message()

This function returns negative error codes, but because the type is u16
they get truncated into positive numbers.  It doesn't look like the
callers care, but we should fix it anyway as a cleanup.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/hv.c

@@ -252,7 +252,7 @@ void hv_cleanup(void)
  *
  * This involves a hypercall.
  */
-u16 hv_post_message(union hv_connection_id connection_id,
+int hv_post_message(union hv_connection_id connection_id,
 		  enum hv_message_type message_type,
 		  void *payload, size_t payload_size)
 {

drivers/hv/hyperv_vmbus.h

@@ -495,7 +495,7 @@ extern int hv_init(void);
 
 extern void hv_cleanup(void);
 
-extern u16 hv_post_message(union hv_connection_id connection_id,
+extern int hv_post_message(union hv_connection_id connection_id,
 			 enum hv_message_type message_type,
 			 void *payload, size_t payload_size);