Revert "drm/bridge: adv7511: Attach to DSI host at probe time"

This reverts commit 83f35bc3

.

There are at least two DSI controller drivers which relies on the old
behaviour of adv7511 driver. To avoid platform breakage this patch
should be reverted. This is a temporary solution, as it blocks adv7511
usage with other platforms.
Assumption that DSI device driver (bridge/panel) should first expose
drm_bridge/drm_panel object, then look for DSI bus is just incorrect -
it can work with devices controlled via i2c but it cannot work with
devices controlled via DSI - they will not be able to probe.
To solve the issue following steps should be performed:
- rework reverted patch allowing co-operation with broken DSI controller
  drivers - with simple/ugly workaround,
- fix controller drivers and then remove workaround.

Signed-off-by: Rob Clark <robdclark@chromium.org>
[a.hajda: changed commit message]
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190829180836.14453-1-robdclark@gmail.com