ARM: pmu: improve PMU type identification

Hi,

This is version 2 of the patches originally posted here:
http://lists.infradead.org/pipermail/linux-arm-kernel/2011-June/052865.html

Changes since v1 include:

* Added Acks from Jamie Iles & Rob Herring.
* Add "arm-pmu" binding to the platform_device_id table, as driver name matching is not used when platform_driver::id_table exists.
* Fixed name clash in PLAT_MATCH_PMU macro.
* Removed unnecessary casts for platform_device_id::driver_data.
* Aligned trailing backslashes on multi-line *_MATCH_PMU macros.
* Removed spaces after casts.

The patches use {of,platform}_device_id tables to provide the PMU type, which can be used similarly (the macros make entries look identical apart from the {plat,of} prefix). This allows us to stop (ab)using platform_device::id, and should allow for easier addition/modification of PMU driver bindings.

BSPs need no longer care about the Type of PMUs they register; as long as a binding exists the type will be assigned correctly.

Rob, Jamie: would you mind if patches 3 & 4 were squashed together? Patch 4 depends heavily on patch 3, and there doesn't seem to be a clean way of fixing that.