drm/meson: fix vsync buffer update

The plane buffer address/stride/height was incorrectly updated in the
plane_atomic_update operation instead of the vsync irq.
This patch delays this operation in the vsync irq along with the
other plane delayed setup.

This issue was masked using legacy framebuffer and X11 modesetting, but
is clearly visible using gbm rendering when buffer is submitted late after
vblank, like using software decoding and OpenGL rendering in Kodi.
With this patch, tearing and other artifacts disappears completely.

Cc: Michal Lazo <michal.lazo@gmail.com>
Fixes: bbbe775e

 ("drm: Add support for Amlogic Meson Graphic Controller")
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1518689976-23292-1-git-send-email-narmstrong@baylibre.com