arm64: dts: imx: Add imx8mp-iota2-lumpy board

The IOTA2 Lumpy board is based on the i.MX8MPlus EVK.

Basic features are:
- 4GB LPDDR4
- 64GB eMMC
- 2x 1GB Ethernet
- USB 3.0 Type-C dual role port, without power delivery
- USB 3.0 Type-A host port
- RGB LED - PWM driven
- speaker - PWM driven
- RTC with super capacitor backup

Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Michal Vokáč <michal.vokac@ysoft.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>