exynos5420: add callbacks needed for exynos_fb driver

Add initialization code for peach_pit panel, parade bridge chip,
and backlight.

Signed-off-by: Ajay Kumar <ajaykumar.rs@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>