drm/exynos: hdmi: remove unnecessary memset

Our resources were just zalloc'ed as part of hdata.
They are already 0.

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Rahul Sharma <Rahul.Sharma@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>