fsl-rio: Add two ports and rapidio message units support

Usually, freescale rapidio endpoint can support one or two 1x or 4X
LP-Serial link interfaces, and rapidio message transactions can be
implemented by two message units. This adds the support of two
rapidio ports and initializes message unit 0 and message unit 1. And
these ports and message units can work simultaneously.

Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Jin Qing <b24347@freescale.com>
Signed-off-by: Liu Gang <Gang.Liu@freescale.com>
Acked-by: Alexandre Bounine <alexandre.bounine@idt.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>