Add lede.ack=1 to kernel commandline when running ACK kernels

Author: gsingh93

Makefile

@@ -420,6 +420,12 @@ ifeq ($(KASLR),0)
   QEMU_KERNEL_CMDLINE += nokaslr
 endif
 
+# This is not an actual kernel parameter, but it allows us to check from within
+# QEMU if this is an ACK kernel or not.
+ifeq ($(ACK),1)
+  QEMU_KERNEL_CMDLINE += lede.ack=1
+endif
+
 QEMU_ARGS += -append "$(QEMU_KERNEL_CMDLINE) $(QEMU_EXTRA_KERNEL_CMDLINE)"
 
 RUN_DEPS := $(QEMU_KERNEL_IMAGE)