ARM: enable LTO for some boards

Enable LTO for some boards that were tested by people on U-Boot Mailing
List.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Tested-by: Adam Ford <aford173@gmail.com>
Tested-by: Pali Rohár <pali@kernel.org>
Tested-by: Tim Harvey <tharvey@gateworks.com>
diff --git a/configs/r8a774a1_beacon_defconfig b/configs/r8a774a1_beacon_defconfig
index 58d3f9f..8e65654 100644
--- a/configs/r8a774a1_beacon_defconfig
+++ b/configs/r8a774a1_beacon_defconfig
@@ -1,3 +1,4 @@
+CONFIG_LTO=y
 CONFIG_ARM=y
 CONFIG_ARCH_RMOBILE=y
 CONFIG_SYS_TEXT_BASE=0x50000000