video: fbdev: Enable Xilinx FB for ZynqMP

Enable this driver for Xilinx ZynqMP.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>