ARM i.MX5: Add system reset controller (SRC) to i.MX51 and i.MX53 device tree

Also, link SRC to IPU via phandle.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>