board: phytec: imx8mp: Add PHYTEC phyCORE-i.MX8MP support

Add initial support PHYTEC phyCORE-i.MX8MP SOM.

    Supported features:
     - 2GB LPDDR4 RAM
     - eMMC
     - external SD
     - debug UART2
     - watchdog

Signed-off-by: Teresa Remmet <t.remmet@phytec.de>
Reviewed-by: Heiko Schocher <hs@denx.de>
13 files changed