fastmodel: Add a wrapper for the CortexR52.

fastmodel: Add a wrapper for the CortexR52.

There has been some testing of this wrapper, but some components are
missing. It's not currently possible to read or set Misc registers,
64 bit integer registers, flattened integer registers, or vector
registers. In some cases that's because no mapping from gem5 indexes
to IRIS resource names has been set up, but in some cases, since R52
is 32 bit, no mapping *can* be set up, and we need to figure out what
to do with requests for 64 bit only state.

Change-Id: I2d650a7c1765b39f25058727502c96e6de5aa26b
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/35635
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>