drm/i915: use hlist_for_each_entry

Use hlist_for_each_entry() instead of hlist_for_each() to simplify
the code.

Signed-off-by: Geliang Tang <geliangtang@163.com>
Link: http://patchwork.freedesktop.org/patch/msgid/b80568b2990ebcc145229a132f045e852ac51ad6.1453126187.git.geliangtang@163.com


Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>