board: phytec: phycore_imx8mp: Add mcore support

Added m7 core support in uboot for imx8mp by adding
the boot variable prepare_mcore.

Based on commit 0ed32cc8568a ("LF-6555 imx8m[m/n/p/q]_evk: add
bootargs to support mcore")

Signed-off-by: Yashwanth Varakala <y.varakala@phytec.de>
1 file changed