ARM: dts: imx6dl-yapp4: Add reg property to the lp5562 channel node

Add the reg property to each channel node.  This update is
to accommodate the multicolor framework.  In addition to the
accommodation this allows the LEDs to be placed on any channel
and allow designs to skip channels as opposed to requiring
sequential order.

Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Dan Murphy <dmurphy@ti.com>
CC: Shawn Guo <shawnguo@kernel.org>
CC: Sascha Hauer <s.hauer@pengutronix.de>
CC: Pengutronix Kernel Team <kernel@pengutronix.de>
CC: Fabio Estevam <festevam@gmail.com>
CC: NXP Linux Team <linux-imx@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>