board: phytec: phycore_am64x: Add Network/SPI Boot

Include the boot logic to boot via Network or from a OSPI/QSPI
NOR flash. Moreover, set all required variables to both boot
methods to the environment.

Note: The phyBOARD-Electra AM64x is not able to load the U-Boot
via Network. However, it's still possible to load the kernel.

Signed-off-by: Daniel Schultz <d.schultz@phytec.de>
diff --git a/board/phytec/phycore_am64x/phycore_am64x.env b/board/phytec/phycore_am64x/phycore_am64x.env
index 18f0fa5..3032b51 100644
--- a/board/phytec/phycore_am64x/phycore_am64x.env
+++ b/board/phytec/phycore_am64x/phycore_am64x.env
@@ -1,4 +1,6 @@
 #include <env/phytec/k3_mmc.env>
+#include <env/phytec/k3_net.env>
+#include <env/phytec/k3_spi.env>
 
 fdtaddr=0x88000000
 loadaddr=0x82000000
@@ -14,3 +16,9 @@
 mmcpart=1
 console=ttyS2,115200n8
 earlycon=ns16550a,mmio32,0x02800000
+
+get_cmd=tftp
+
+spi_fdt_addr=0x700000
+spi_image_addr=0x800000
+spi_ramdisk_addr=0x1e00000