virt: vbox: Add vbg_set_host_capabilities() helper function

Add vbg_set_host_capabilities() helper function,  this is a preparation
patch for adding support for the VBGL_IOCTL_GUEST_CAPS_ACQUIRE ioctl.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20200709120858.63928-5-hdegoede@redhat.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>