Enable VLAN_CMD in ipxe

In order to support vlan tagging during the boot process, enable
VLAN_CMD in ipxe.

Documented at https://ipxe.org/cmd/vcreate

Signed-off-by: Jonathon Anderson <janderson@ciq.co>

ipxe-update.sh

@@ -25,6 +25,7 @@ sed -i.bak \
 sed -i.bak \
     -e 's,//\(#define.*IMAGE_ZLIB.*\),\1,' \
     -e 's,//\(#define.*IMAGE_GZIP.*\),\1,' \
+    -e 's,//\(#define.*VLAN_CMD.*\),\1,' \
     config/general.h
 
 make -j 8 $PCBIOS