Fix small 'case' typo in image-fit.c

This typo makes the comment confusing. Fix it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/image-fit.c b/common/image-fit.c
index c0d7b8c..83fac9a 100644
--- a/common/image-fit.c
+++ b/common/image-fit.c
@@ -1637,7 +1637,7 @@
 
 	/*
 	 * Work-around for eldk-4.2 which gives this warning if we try to
-	 * case in the unmap_sysmem() call:
+	 * cast in the unmap_sysmem() call:
 	 * warning: initialization discards qualifiers from pointer target type
 	 */
 	{