imx:mx6slevk support reading temperature

This patch is to support reading temperature for mx6slevk board.

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
diff --git a/configs/mx6slevk_defconfig b/configs/mx6slevk_defconfig
index fb8c4de..c6b3108 100644
--- a/configs/mx6slevk_defconfig
+++ b/configs/mx6slevk_defconfig
@@ -1,3 +1,7 @@
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/freescale/mx6slevk/imximage.cfg,MX6SL"
 CONFIG_ARM=y
 CONFIG_TARGET_MX6SLEVK=y
+CONFIG_SYS_MALLOC_F=y
+CONFIG_SYS_MALLOC_F_LEN=0x400
+CONFIG_DM=y
+CONFIG_DM_THERMAL=y