drm/tegra: kick out simplefb

Kick out firmware fb when loading Tegra driver.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/b5c3972e5774d0d1f8887054a993bbc54e9dbe2a.1535810304.git.mirq-linux@rere.qmqm.pl