Allow the mapping code to request a specific virtual address for the gem
mapping. If the virtual address is zero we fall back to the old mode of
allocating a virtual address for the mapping.
Signed-off-by: NLucas Stach <l.stach@pengutronix.de>
Reviewed-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: NGuido Günther <agx@sigxcpu.org>