Revert "drm/exynos: Don't reset bridge->next"

This reverts commit 2c33a614.

It breaks the Android kernel api and was added only because of a tiny
drm driver bugfix for an issue that can not ever really be hit, so it is
safe to revert.

Bug: 161946584
Change-Id: I5af931c4a83aded53bba654a9966c2ffab010d46
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>