smartweb: Enable LTO

In order to prepare for slight size growth due to reworking linker list
support, enable LTO here to save more space again.

Signed-off-by: Tom Rini <trini@konsulko.com>
---
Cc: Heiko Schocher <hs@denx.de>
diff --git a/configs/smartweb_defconfig b/configs/smartweb_defconfig
index 4cbdab0..836e0c0 100644
--- a/configs/smartweb_defconfig
+++ b/configs/smartweb_defconfig
@@ -24,6 +24,7 @@
 CONFIG_SPL=y
 CONFIG_ENV_OFFSET_REDUND=0x180000
 CONFIG_SYS_LOAD_ADDR=0x22000000
+CONFIG_LTO=y
 CONFIG_FIT=y
 CONFIG_NAND_BOOT=y
 CONFIG_BOOTDELAY=3