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>

Basically the same as for i.MX8MQ, just some function split up needed
to account for different base addresses for the TF-A on both SoCs.

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

Add imx8mq_atf_load_bl31() containing all of the code needed to load
and transfer control to BL31 ATF blob on i.MX8M.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>