Staging: hv: remove GetChannelInfo from struct vmbus_driver

It was only set to one value, so just make the call to
get_channel_info() directly.

Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>