This adds base support for the i.MX8MP SoC. Not much to do here as this
SoC is quite similar to the i.MX8M. This adds:

- Kconfig symbols
- bootsource detection
- register base address defines
- iomux defines

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>

This adds support for the i.MX8MM.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

The i.MX8M boards all have the same code for setting up the UART clock.
Add a common helper for it. In the helper just setup the clocks for all
UARTs as it's not worth it to have separate functions for each UART.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

U-Boot has some lowlevel clock functions which take a clock slice index
as argument. Add them for barebox as well to make the code better
comparable to U-Boot.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Those will differ between i.MX8MQ and i.MX8MM, so give them the
appropriate prefix before introducing i.MX8MM support.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Most of the code in imx8mq.c can be reused for i.MX8MM, so rename it
and compile depending on CONFIG_ARCH_IMX8M.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>