dts: peach_pit: Add SLP and RST GPIO properties in parade DT node

Now that parade driver supports reading SLP and RST GPIO
from DT, specify the same in parade DT node.

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