Remove flatbuffers targets

flatbuffers is removed from the manifest and not used in the repo

Change-Id: Ia5295b5fd6c6fc62d4d381f1a295e8ffb5e2db86
diff --git a/Makefile b/Makefile
index 5f00742..69f98b6 100644
--- a/Makefile
+++ b/Makefile
@@ -30,7 +30,6 @@
 include $(ROOTDIR)/build/cantrip_sel4test.mk
 include $(ROOTDIR)/build/cantrip_tests.mk
 include $(ROOTDIR)/build/minisel.mk
-include $(ROOTDIR)/build/flatbuffers.mk
 include $(ROOTDIR)/build/verilator.mk
 
 include $(ROOTDIR)/build/platforms/$(PLATFORM)/platform.mk
diff --git a/flatbuffers.mk b/flatbuffers.mk
deleted file mode 100644
index c71b876..0000000
--- a/flatbuffers.mk
+++ /dev/null
@@ -1,42 +0,0 @@
-# Copyright 2022 Google LLC
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-FLATBUFFERS_SRC_DIR     := $(ROOTDIR)/sw/flatbuffers
-FLATBUFFERS_BUILD_DIR   := $(OUT)/flatbuffers
-FLATBUFFERS_INSTALL_DIR := $(OUT)/host/flatbuffers
-FLATBUFFERS_FLATC       := $(OUT)/host/flatbuffers/bin/flatc
-
-# NB: We only need to depend on some of the files in the host source tree from
-# the flatbuffers repo, so a simple single directory wildcard should suffice for
-# determining when we need to rebuild this target.
-FLATBUFFERS_SRCS := $(wildcard $(FLATBUFFERS_SRC_DIR)/src/*)
-
-$(FLATBUFFERS_BUILD_DIR):
-	mkdir -p $(FLATBUFFERS_BUILD_DIR)
-
-$(FLATBUFFERS_FLATC): $(FLATBUFFERS_SRCS) | $(FLATBUFFERS_BUILD_DIR)
-	cmake -S $(FLATBUFFERS_SRC_DIR) -B $(FLATBUFFERS_BUILD_DIR) -G Ninja \
-		-DCMAKE_INSTALL_PREFIX=$(FLATBUFFERS_INSTALL_DIR)
-	ninja -C $(OUT)/flatbuffers install
-
-## Builds and installs the flatbuffers host tooling
-#
-# Output is placed in the out/host/flatbuffers tree.
-flatbuffers: $(FLATBUFFERS_FLATC)
-
-## Cleans up the flatbuffers binaries
-flatbuffers-clean:
-	rm -rf $(FLATBUFFERS_BUILD_DIR) $(FLATBUFFERS_INSTALL_DIR)
-
-.PHONY:: flatbuffers