[POWERPC] Create Marvell mv64x60 MPSC (serial) platform_data

This patch creates platform_device entries for the Marvell mv64x60
MPSC (multi-protocol serial controller) ports, based on information
contained in the device tree.

This driver (like the other mv64x60 drivers) are unusual in that it
works on both the MIPS and PowerPC architectures.  Because of that,
the drivers do not support the normal PowerPC of_platform_bus_type.
They support platform_bus_type instead.

Signed-off-by: Dale Farnsworth <dale@farnsworth.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>