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>
2 files changed