drm/exynos: Add missing braces around sizeof in exynos_hdmi.c

Fixes the following checkpatch warnings:
WARNING: sizeof *res should be sizeof(*res)
WARNING: sizeof res->regul_bulk[0] should be sizeof(res->regul_bulk[0])
WARNING: sizeof *res should be sizeof(*res)

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>