memory: pl172: fix modular build

Building pl172 as a module fails with:
> ERROR: "of_default_bus_match_table" [drivers/memory/pl172.ko] undefined!

Because the symbol of_default_bus_match_table isn't exported by the OF
core code so can't be referenced from modules. Fix this by removing
the usage of of_default_bus_match_table for now. The side effect of
this is that child nodes can't use "simple-bus" or "simple-mfd".

Reported-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Olof Johansson <olof@lixom.net>