bk4r1: Enable LTO

In order to allow for general platform growth due to fixes, enable LTO
here to give us more room.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/bk4r1_defconfig b/configs/bk4r1_defconfig
index 66adeac..95f0c30 100644
--- a/configs/bk4r1_defconfig
+++ b/configs/bk4r1_defconfig
@@ -18,6 +18,7 @@
 CONFIG_SYS_LOAD_ADDR=0x82000000
 CONFIG_SYS_MEMTEST_START=0x80010000
 CONFIG_SYS_MEMTEST_END=0x87c00000
+CONFIG_LTO=y
 CONFIG_HAS_BOARD_SIZE_LIMIT=y
 CONFIG_BOARD_SIZE_LIMIT=520192
 CONFIG_FIT=y