Endian conversion: move to platform.h and platform/endian*.c

Starting to move the platform dependent code to platform/ and provide
the abstraction through the platform.h header.

Change-Id: I35640282d451960f2a329ae24339ec05dbae6d30
Signed-off-by: Thomas Heijligen <thomas.heijligen@secunet.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/62899
Original-Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/72316
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/Makefile b/Makefile
index 7692b98..64e6fb8 100644
--- a/Makefile
+++ b/Makefile
@@ -383,7 +383,7 @@
 # Library code.
 
 LIB_OBJS = libflashrom.o layout.o flashrom.o udelay.o programmer.o programmer_table.o \
-	helpers.o ich_descriptors.o fmap.o hwaccess_endian_$(ENDIAN).o
+	helpers.o ich_descriptors.o fmap.o platform/endian_$(ENDIAN).o
 
 
 ###############################################################################
@@ -952,7 +952,8 @@
 # This includes all frontends and libflashrom.
 # We don't use EXEC_SUFFIX here because we want to clean everything.
 clean:
-	rm -f $(PROGRAM) $(PROGRAM).exe libflashrom.a $(filter-out Makefile.d, $(wildcard *.d *.o)) $(PROGRAM).8 $(PROGRAM).8.html $(BUILD_DETAILS_FILE)
+	rm -f $(PROGRAM) $(PROGRAM).exe libflashrom.a $(filter-out Makefile.d, $(wildcard *.d *.o platform/*.d platform/*.o)) \
+		$(PROGRAM).8 $(PROGRAM).8.html $(BUILD_DETAILS_FILE)
 	@+$(MAKE) -C util/ich_descriptors_tool/ clean
 
 install: $(PROGRAM)$(EXEC_SUFFIX) $(PROGRAM).8