perf/arm-cci: Untangle global cci_ctrl_base

Depending directly on the bus driver's global cci_ctrl_base variable
is a little unpleasant, and exporting it to allow the PMU driver to
be modular would be even more so. Let's make things a little better
abstracted by adding the control register block to the cci_pmu instance
data alongside the PMU register block, and communicating the mapped
address from the bus driver via platform data.

It's not practical to try the same thing for the bus driver itself,
given that the globals are entangled with the hairy assembly code for
port control, so we leave them be there. It would however be prudent
to move them to the __ro_after_init section in passing, since the
addresses really should never be changing once set.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>