drm/vc4: Add support for X/Y reflection

Add support for X/Y reflection when the plane is using linear or
T-tiled formats. X/Y reflection hasn't been tested on SAND formats, so
we reject them until proper testing/debugging has been done.

Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20181207083606.15449-2-boris.brezillon@bootlin.com