Staging: hv: hv_mouse: fix up copyright and license header

Use the proper license header from the other hv drivers and remove the
nonsense about derivative works, as it's rubbish.

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