drm: qxl: ensure surf.data is ininitialized

drm: qxl: ensure surf.data is ininitialized

The object surf is not fully initialized and the uninitialized
field surf.data is being copied by the call to qxl_bo_create
via the call to qxl_gem_object_create. Set surf.data to zero
to ensure garbage data from the stack is not being copied.

Addresses-Coverity: ("Uninitialized scalar variable")
Fixes: f64122c1f6ad ("drm: add new QXL driver. (v1.4)")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20210608161313.161922-1-colin.king@canonical.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>