drm/rockchip: analogix_dp: Remove unnecessary init code

Remove unnecessary init code, since we would do it in the power_on()
callback.

Also move of parse code to probe().

Fixes: 9e32e16e ("drm: rockchip: dp: add rockchip platform dp driver")
Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Acked-by: Mark Yao <mark.yao@rock-chips.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20171019034812.13768-3-jeffy.chen@rock-chips.com