sh: sh2a MTU2 platform data

This patch adds MTU2 platform data for the following cpus:
 - sh7201 (3/5 channels)
 - sh7203/sh7263 (2/4 channels)
 - sh7206 (3/5 channels)
 - MXG (3/5 channels)

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>