wandboard: README: Include the mx6qp variant in the list

The mx6qp Wandboard variant is also supported, so add it to the list.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
diff --git a/board/wandboard/README b/board/wandboard/README
index 6345416..e5170bc 100644
--- a/board/wandboard/README
+++ b/board/wandboard/README
@@ -4,7 +4,7 @@
 This file contains information for the port of U-Boot to the Wandboard.
 
 Wandboard is a development board that has three variants based on the following
-SoCs: mx6 quad, mx6 dual lite and mx6 solo.
+SoCs: mx6 quad, mx6 quad plus, mx6 dual lite and mx6 solo.
 
 For more details about Wandboard, please refer to:
 http://www.wandboard.org/