Fixes a build failure with mediatek.

This change was supposed to be part of commit 49a3f51d ("drm/gem:
Use struct dma_buf_map in GEM vmap ops and convert GEM backends"), but
mediatek was forgotten.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Fixes: 49a3f51d ("drm/gem: Use struct dma_buf_map in GEM vmap ops and convert GEM backends")
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Christian König <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Russell King <linux+etnaviv@armlinux.org.uk>
Cc: Christian Gmeiner <christian.gmeiner@gmail.com>
Cc: Qiang Yu <yuq825@gmail.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Steven Price <steven.price@arm.com>
Cc: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: Sandy Huang <hjc@rock-chips.com>
Cc: "Heiko Stübner" <heiko@sntech.de>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Sean Paul <sean@poorly.run>
Cc: Eric Anholt <eric@anholt.net>
Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Cc: Melissa Wen <melissa.srw@gmail.com>
Cc: Haneen Mohammed <hamohammed.sa@gmail.com>
Cc: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Emil Velikov <emil.velikov@collabora.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Arunpravin <apaneers@amd.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: Luben Tuikov <luben.tuikov@amd.com>
Cc: Madhav Chauhan <madhav.chauhan@amd.com>
Cc: Nirmoy Das <Nirmoy.Das@amd.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: dri-devel@lists.freedesktop.org
Cc: etnaviv@lists.freedesktop.org
Cc: lima@lists.freedesktop.org
Cc: nouveau@lists.freedesktop.org
Cc: virtualization@lists.linux-foundation.org
Cc: spice-devel@lists.freedesktop.org
Cc: amd-gfx@lists.freedesktop.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-rockchip@lists.infradead.org
Cc: xen-devel@lists.xenproject.org
Link: https://patchwork.freedesktop.org/patch/msgid/20201109103242.19544-3-tzimmermann@suse.de