configs/freescale_imx8mpevk: new defconfig

configs/freescale_imx8mpevk: new defconfig

This patch adds support for the NXP i.MX 8M Plus EVK board [1].

The final boot image is created from uboot and firmware binaries in post
image script board/freescale/common/imx/imx8-bootloader-prepare.sh.

This first support is based on NXP's 5.4.70_2.3.0 BSP.

[1] https://www.nxp.com/design/development-boards/i-mx-evaluation-and-development-boards/evaluation-kit-for-the-i-mx-8m-plus-applications-processor:8MPLUSLPD4-EVK

Signed-off-by: Stephane Viau <stephane.viau@oss.nxp.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>