ARM: fix LTO for seaboard

When seaboard_defconfig is compiled with LTO, the compiler complains
about some instructions not being supported in ARM mode.

This is caused by arch/arm/mach-tegra/tegra20/warmboot_avp.c having
different CFLAGS declared in Makefile. This file needs to be compiled
without LTO.

Fix this by removing -flto for this file.
Signed-off-by: NMarek Behún <marek.behun@nic.cz>
Reviewed-by: NSimon Glass <sjg@chromium.org>

arch/arm/mach-tegra/tegra20/Makefile

@@ -10,6 +10,7 @@ endif
 # flags for any startup files it might use.
 CFLAGS_warmboot_avp.o = -march=armv4t -U__LINUX_ARM_ARCH__ \
 	-D__LINUX_ARM_ARCH__=4
+CFLAGS_REMOVE_warmboot_avp.o := $(LTO_CFLAGS)
 
 obj-y	+= clock.o funcmux.o pinmux.o
 obj-$(CONFIG_TEGRA_LP0) += warmboot.o crypto.o warmboot_avp.o