sandbox: spl: enable lmb config for SPL

Enable the LMB config in SPL. This helps in testing the LMB code in
SPL on sandbox.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/sandbox_noinst_defconfig b/configs/sandbox_noinst_defconfig
index bfd95e2..eb0f064 100644
--- a/configs/sandbox_noinst_defconfig
+++ b/configs/sandbox_noinst_defconfig
@@ -286,3 +286,4 @@
 CONFIG_SPL_UNIT_TEST=y
 CONFIG_UT_TIME=y
 CONFIG_UT_DM=y
+CONFIG_SPL_LMB=y