drm/ttm, drm/vmwgfx: Relax permission checking when opening surfaces

drm/ttm, drm/vmwgfx: Relax permission checking when opening surfaces

BugLink: http://bugs.launchpad.net/bugs/1682130
commit fe25deb7737ce6c0879ccf79c99fa1221d428bf2 upstream.

Previously, when a surface was opened using a legacy (non prime) handle,
it was verified to have been created by a client in the same master realm.
Relax this so that opening is also allowed recursively if the client
already has the surface open.

This works around a regression in svga mesa where opening of a shared
surface is used recursively to obtain surface information.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>