Revert "drm/mipi-dsi: Fix detach call without attach"

This reverts commit 67997250 which is
commit 90d50b8d upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Ib35a1ec2def2ed5bc40a2dd58a7c2fa981477538
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>