drm/rockchip: dw-mipi-dsi: configure PHY before enabling

The bias, bandgap and PLL should all be configured before we enable
them.

Signed-off-by: John Keeping <john@metanate.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170224125506.21533-16-john@metanate.com