When binding the TCON, we were checking the reset control status and
asserting reset if it wasn't in reset. The check failed to account for
the reset control API returning error codes if the status callback was
not implemented.

Since we want the TCON to be reset in all cases, use reset_control_reset
to force a reset instead.

Fixes: 9026e0d1 ("drm: Add Allwinner A10 Display Engine support")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170908090016.32224-1-wens@csie.org