kernel: Clean up kernel copy recipes

ACP and ALL_PREBUILT are dropped years ago and thus have become no-ops.

Change-Id: Ic317cb4a4fa406cce0dc86555fb8da34d21fb2bf
diff --git a/build/tasks/kernel.mk b/build/tasks/kernel.mk
index 9b8c873..a6aacfd 100644
--- a/build/tasks/kernel.mk
+++ b/build/tasks/kernel.mk
@@ -494,21 +494,13 @@
 ## Install it
 
 ifeq ($(NEEDS_KERNEL_COPY),true)
-file := $(INSTALLED_KERNEL_TARGET)
-ALL_PREBUILT += $(file)
-$(file) : $(KERNEL_BIN) | $(ACP)
+$(INSTALLED_KERNEL_TARGET): $(KERNEL_BIN)
 	$(transform-prebuilt-to-target)
-
-ALL_PREBUILT += $(INSTALLED_KERNEL_TARGET)
 endif
 
 ifeq ($(RECOVERY_KERNEL_COPY),true)
-file := $(INSTALLED_RECOVERY_KERNEL_TARGET)
-ALL_PREBUILT += $(file)
-$(file) : $(RECOVERY_BIN) | $(ACP)
+$(INSTALLED_RECOVERY_KERNEL_TARGET): $(RECOVERY_BIN)
 	$(transform-prebuilt-to-target)
-
-ALL_PREBUILT += $(INSTALLED_RECOVERY_KERNEL_TARGET)
 endif
 
 .PHONY: recovery-kernel