Fix spelling of "extended".

Signed-off-by: Vagrant Cascadian <vagrant@debian.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/bootm.c b/cmd/bootm.c
index e02a1c5..083f3d1 100644
--- a/cmd/bootm.c
+++ b/cmd/bootm.c
@@ -162,7 +162,7 @@
 #endif
 #if defined(CONFIG_FIT)
 	"\t\nFor the new multi component uImage format (FIT) addresses\n"
-	"\tmust be extened to include component or configuration unit name:\n"
+	"\tmust be extended to include component or configuration unit name:\n"
 	"\taddr:<subimg_uname> - direct component image specification\n"
 	"\taddr#<conf_uname>   - configuration specification\n"
 	"\tUse iminfo command to get the list of existing component\n"