sh: sh4a scif pdata (sh7757/sh7763/sh7770/sh7780/sh7785/sh7786/x3)

This patch breaks out the sh4a scif serial port platform
data from a shared platform device to one platform
device per port. Also, add serial ports to the list of
early platform devices.

All sh4a except SuperH Mobile processors are modified by
this patch.

While at it, sh7757 gets early platform device support.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>