octeon: mark source-only

There is a hard to reproduce, even harder to track down memory leak in
Octeon since kernel 5.10. Mark octeon source-only until it is plugged.

Signed-off-by: Stijn Tintel <[email protected]>

target/linux/octeon/Makefile

@@ -7,7 +7,7 @@ include $(TOPDIR)/rules.mk
 ARCH:=mips64
 BOARD:=octeon
 BOARDNAME:=Cavium Networks Octeon
-FEATURES:=squashfs ramdisk pci usb
+FEATURES:=squashfs ramdisk pci source-only usb
 CPU_TYPE:=octeonplus
 
 KERNEL_PATCHVER:=5.10