powerpc/85xx: don't call of_platform_bus_probe() twice

Commit 46d026ac

 ("powerpc/85xx: consolidate of_platform_bus_probe calls")
replaced platform-specific of_device_id tables with a single function
that probes the most of the busses in 85xx device trees.  If a specific
platform needed additional busses probed, then it could call
of_platform_bus_probe() again.  Typically, the additional platform-specific
busses are children of existing busses that have already been probed.
of_platform_bus_probe() does not handle those child busses automatically.

Unfortunately, this doesn't actually work.  The second (platform-specific)
call to of_platform_bus_probe() never finds any of the busses it's asked
to find.

To remedy this, the platform-specific of_device_id tables are eliminated,
and their entries are merged into mpc85xx_common_ids[], so that all busses
are probed at once.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>