staging: vt6655: Fix memory leak in vt6655_probe

In vt6655_probe, if vnt_init() fails the cleanup code needs to be called
like other error handling cases. The call to device_free_info() is
added.

Fixes: 67013f2c

 ("staging: vt6655: mac80211 conversion add main mac80211 functions")
Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191004200319.22394-1-navid.emamdoost@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>