powerpc/t4240rdb: Add alternate SerDes 2 protocol to align with RCW

SerDes 2 protocol 56 is not valid any longer due to
the new RCW; protocol 55 is used instead, so add
SerDes 2 protocol 55 to align with RCW.

Signed-off-by: Chunhe Lan <Chunhe.Lan@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>
diff --git a/board/freescale/t4rdb/t4_rcw.cfg b/board/freescale/t4rdb/t4_rcw.cfg
index fdbbe5e..e46c7b2 100644
--- a/board/freescale/t4rdb/t4_rcw.cfg
+++ b/board/freescale/t4rdb/t4_rcw.cfg
@@ -1,7 +1,7 @@
 #PBL preamble and RCW header
 aa55aa55 010e0100
-#serdes protocol  27_56_1_9
+#serdes protocol  27_55_1_9
 16070019 18101916 00000000 00000000
-6c700848 00448c00 6c020000 f5000000
+6c6e0848 00448c00 6c020000 f5000000
 00000000 ee0000ee 00000000 000287fc
 00000000 50000000 00000000 00000028