Revert "Import firmware compiler flags"

Makefile

Index: Makefile
diff --git a/Makefile b/Makefile
index 94d1f0279bbf6eaf4678cd1393d6d3164ecc45f0..36250fb67df56a76791c1e34ba88eab4887dc907 100644
--- a/Makefile
+++ b/Makefile
@@ -3,33 +3,19 @@
 # found in the LICENSE file.
 
 export FIRMWARE_ARCH
-export FIRMWARE_CONFIG_PATH
 
 export CC ?= gcc
 export CXX ?= g++
-export CFLAGS
-
-# Include compiler flags if provided.
-# The CC and CFLAGS should not be overridden hereafter.
-ifneq ($(FIRMWARE_CONFIG_PATH),)
-include $(FIRMWARE_CONFIG_PATH)
-endif
-
-# Provides default optimization level if not set by FIRMWARE_CONFIG_PATH
-ifeq (${DEBUG},)
-CFLAGS ?= -O3
-else
-CFLAGS ?= -O0
-endif
-
 ifeq ($(FIRMWARE_ARCH),)
-CFLAGS += -Wall -Werror -DCHROMEOS_ENVIRONMENT
+export CFLAGS = -Wall -Werror -DCHROMEOS_ENVIRONMENT
 else
-CFLAGS += -Wall -Werror
+export CFLAGS = -Wall -Werror
 endif
 
-ifneq (${DEBUG},)
-CFLAGS += -g -DVBOOT_DEBUG
+ifeq (${DEBUG},)
+CFLAGS += -O3
+else
+CFLAGS += -O0 -g -DVBOOT_DEBUG
 endif
 
 ifeq (${DISABLE_NDEBUG},)