hv: remove free_channel() from hyperv.h

This function is only used in the file it is declared in
(channel_mgmt.c) so make it static and remove it from the hyperv.h file.

Cc: K. Y. Srinivasan <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/hv/channel_mgmt.c

···
 /*
  * free_channel - Release the resources used by the vmbus channel object
  */
-void free_channel(struct vmbus_channel *channel)
+static void free_channel(struct vmbus_channel *channel)
 {
 
 	/*

include/linux/hyperv.h

···
 	void *channel_callback_context;
 };
 
-void free_channel(struct vmbus_channel *channel);
-
 void vmbus_onmessage(void *context);
 
 int vmbus_request_offers(void);