Fix two typos.

Signed-off-by: Detlev Zundel <dzu@denx.de>
diff --git a/common/cmd_dtt.c b/common/cmd_dtt.c
index 8da95bf..804d467 100644
--- a/common/cmd_dtt.c
+++ b/common/cmd_dtt.c
@@ -57,7 +57,7 @@
 
 U_BOOT_CMD(
 	  dtt,	1,	1,	do_dtt,
-	  "dtt     - Digital Thermometer and Themostat\n",
+	  "dtt     - Digital Thermometer and Thermostat\n",
 	  "        - Read temperature from digital thermometer and thermostat.\n"
 );