cmd: fix dependency for CMD_CLS

It seems this symbol was missed when renaming DM_VIDEO -> VIDEO.  Update
it.

Fixes: b86986c7b3 ("video: Rename CONFIG_DM_VIDEO to CONFIG_VIDEO")
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: John Keeping <john@metanate.com>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 1092fb9..79848cc 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1959,7 +1959,7 @@
 
 config CMD_CLS
 	bool "Enable clear screen command 'cls'"
-	default y if LCD || DM_VIDEO
+	default y if LCD || VIDEO
 	help
 	  Enable the 'cls' command which clears the screen contents
 	  on video frame buffer.