Add the missing dependency on BOARD_PREBUILT_DTBOIMAGE.

Test: Use a target that defines `BOARD_INCLUDE_RECOVERY_DTBO := true`
      and BOARD_PREBUILT_DTBOIMAGE. Touching a prebuilt dtbo file
      triggers rebuilding of recovery image.
Change-Id: Icf44032fb29542c6836a401c79fb85345ad6cc3c
diff --git a/core/Makefile b/core/Makefile
index ecca965..cc5a6e0 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1662,6 +1662,10 @@
 ifeq (true,$(BOARD_AVB_ENABLE))
 $(INSTALLED_BOOTIMAGE_TARGET) : $(AVBTOOL) $(BOARD_AVB_BOOT_KEY_PATH)
 endif
+ifdef BOARD_INCLUDE_RECOVERY_DTBO
+$(INSTALLED_BOOTIMAGE_TARGET): $(BOARD_PREBUILT_DTBOIMAGE)
+endif
+
 $(INSTALLED_BOOTIMAGE_TARGET): $(MKBOOTFS) $(MKBOOTIMG) $(MINIGZIP) \
 		$(INSTALLED_RAMDISK_TARGET) \
 		$(INTERNAL_RECOVERYIMAGE_FILES) \
@@ -1673,8 +1677,12 @@
 		$(RECOVERY_INSTALL_OTA_KEYS) \
 		$(BOARD_RECOVERY_KERNEL_MODULES) \
 		$(DEPMOD)
-		$(call pretty,"Target boot image from recovery: $@")
-		$(call build-recoveryimage-target, $@)
+	$(call pretty,"Target boot image from recovery: $@")
+	$(call build-recoveryimage-target, $@)
+endif # BOARD_USES_RECOVERY_AS_BOOT
+
+ifdef BOARD_INCLUDE_RECOVERY_DTBO
+$(INSTALLED_RECOVERYIMAGE_TARGET): $(BOARD_PREBUILT_DTBOIMAGE)
 endif
 
 $(INSTALLED_RECOVERYIMAGE_TARGET): $(MKBOOTFS) $(MKBOOTIMG) $(MINIGZIP) \
@@ -1689,7 +1697,7 @@
 		$(RECOVERY_INSTALL_OTA_KEYS) \
 		$(BOARD_RECOVERY_KERNEL_MODULES) \
 		$(DEPMOD)
-		$(call build-recoveryimage-target, $@)
+	$(call build-recoveryimage-target, $@)
 
 ifdef RECOVERY_RESOURCE_ZIP
 $(RECOVERY_RESOURCE_ZIP): $(INSTALLED_RECOVERYIMAGE_TARGET) | $(ZIPTIME)