ARM: make LTO available

Make LTO available for ARM architecture.
Signed-off-by: NMarek Behún <marek.behun@nic.cz>
Reviewed-by: NSimon Glass <sjg@chromium.org>

arch/Kconfig

@@ -33,6 +33,7 @@ config ARC
 
 config ARM
 	bool "ARM architecture"
+	select ARCH_SUPPORTS_LTO
 	select CREATE_ARCH_SYMLINK
 	select HAVE_PRIVATE_LIBGCC if !ARM64
 	select SUPPORT_OF_CONTROL

arch/arm/lib/Makefile

@@ -45,6 +45,8 @@ obj-$(CONFIG_SEMIHOSTING) += semihosting.o
 
 obj-y	+= bdinfo.o
 obj-y	+= sections.o
+CFLAGS_REMOVE_sections.o := $(LTO_CFLAGS)
+
 obj-y	+= stack.o
 ifdef CONFIG_CPU_V7M
 obj-y	+= interrupts_m.o