include: env: phytec: Add optargs to K3 files

Add the optargs variable so that we can set optional arguments while
booting.

Signed-off-by: Nathan Morrisson <nmorrisson@phytec.com>
Signed-off-by: Daniel Schultz <d.schultz@phytec.de>
diff --git a/include/env/phytec/k3_net.env b/include/env/phytec/k3_net.env
index 377e406..8ad1cb7 100644
--- a/include/env/phytec/k3_net.env
+++ b/include/env/phytec/k3_net.env
@@ -9,7 +9,7 @@
 #include <env/phytec/overlays.env>
 
 netargs=setenv bootargs console=${console} root=/dev/nfs ip=dhcp rw
-	nfsroot=${serverip}:${nfsroot},vers=4,tcp
+	nfsroot=${serverip}:${nfsroot},vers=4,tcp ${optargs}
 netloadimage=${net_fetch_cmd} ${kernel_addr_r} ${serverip}:/Image
 netloadfdt=${net_fetch_cmd} ${fdt_addr_r} ${serverip}:/${fdtfile}
 netboot=run netargs;