style: [patch 3/22] reduce include dependencies in some headers

Used cppclean to help identify useless includes and removed them. This
involved erroneously included headers, but also cases where forward
declarations could have been used rather than a full include.

pwr: Closing power and thermal feedback loop

This patch makes thermal models use the power figures
calculated by power models. Since there is a circular
dependency between power and thermal (and thermal was
pushed before) this patch closes that loop.

Change-Id: I8bd5acf6a5026fdbbcfac47e33d27397f24a6f7d
Reviewed-by: Stephan Diestelhorst <stephan.diestelhorst@arm.com>

stats: Fixing regStats function for some SimObjects

Fixing an issue with regStats not calling the parent class method
for most SimObjects in Gem5. This causes issues if one adds new
stats in the base class (since they are never initialized properly!).

Change-Id: Iebc5aa66f58816ef4295dc8e48a357558d76a77c
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

Revert power patch sets with unexpected interactions

The following patches had unexpected interactions with the current
upstream code and have been reverted for now:

e07fd01651f3: power: Add support for power models
831c7f2f9e39: power: Low-power idle power state for idle CPUs
4f749e00b667: power: Add power states to ClockedObject

Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>

power: Add support for power models

This patch adds some basic support for power models in gem5.

The power interface is defined so it can interact with thermal
models as well. It implements a simple power evaluator that
can be used for simple power models that express power in the
form of a math expression. These expressions can use stats
within the same SimObject (or down its hierarchy) and some
magic variables such as "temp" for temperature.
In future patches we will extend this functionality to allow
slightly more complex expressions.

The model allows it to be extended to use other kinds of models.

Finally, the thermal model is updated to use the power usage as input.

sim: Adding thermal model support

This patch adds basic thermal support to gem5. It models energy dissipation
through a circuital equivalent, which allows us to use RC networks.
This lays down the basic infrastructure to do so, but it does not "work" due
to the lack of power models. For now some hardcoded number is used as a PoC.
The solver is embedded in the patch.