Support for NXP iMX8MQ added to -current

[Jared McNeill <jmcneill%invisible.ca@localhost>]

Hi folks --

I've committed support for the NXP iMX8MQ family SoC to NetBSD -current.

To make a bootable image from arm64.img:

 $ ftp https://images.solid-build.xyz/IMX8/U-Boot/u-boot-imx8mq-sdhc.bin
 $ dd if=u-boot-imx8mq-sdhc.bin of=arm64.img bs=1k seek=32 conv=notrunc

In U-Boot you will have to change the fdtfile and fdt_file environment 
variables to point to the correct dtb (the default ones have a fsl- prefix 
that is not used by mainline Linux dts files):

 => setenv fdtfile imx8mq-hummingboard-pulse.dtb
 => setenv fdt_file imx8mq-hummingboard-pulse.dtb
 => saveenv
 => reset

What works so far:

 - UART console
 - FEC ethernet
 - USB 3.0 host mode
 - I2C
 - GPIO
 - MicroSD slot

dmesg: https://dmesgd.nycbug.org/index.cgi?do=view&id=5310

Cheers,
Jared