staging: vboxvideo: Fix reporting invalid suggested-offset-properties

staging: vboxvideo: Fix reporting invalid suggested-offset-properties

BugLink: http://bugs.launchpad.net/bugs/1744212
commit ce10d7b4e8e3574b9616e54a09d64521b9aeb8b6 upstream.

The x and y hints receives from the host are unsigned 32 bit integers and
they get set to -1 (0xffffffff) when invalid. Before this commit the
vboxvideo driver was storing them in an u16 causing the -1 to be truncated
to 65535 which, once reported to userspace, was breaking gnome 3.26+
in Wayland mode.

This commit stores the host values in 32 bit variables, removing the
truncation and checks for -1, replacing it with 0 as -1 is not a valid
suggested-offset-property value. Likewise the properties are now
initialized to 0 instead of -1, since -1 is not a valid value.
This fixes gnome 3.26+ in Wayland mode not working with the vboxvideo
driver.

Reported-by: Gianfranco Costamagna <locutusofborg@debian.org>
Cc: Michael Thayer <michael.thayer@oracle.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>