- Model borrowed from target/sh4/cpu.c
- Rewrote riscv_cpu_list to use object_class_get_list
- Dropped 'struct RISCVCPUInfo' and used TypeInfo array
- Replaced riscv_cpu_register_types with DEFINE_TYPES
- Marked base class as abstract
- Fixes -cpu list

Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Sagar Karandikar <sagark@eecs.berkeley.edu>
Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Cc: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: NMichael Clark <mjc@sifive.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: NIgor Mammedov <imammedo@redhat.com>

This version uses a constant size memory buffer sized for
the maximum possible ISA string length. It also uses g_new
instead of g_new0, uses more efficient logic to append
extensions and adds manual zero termination of the string.

Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: NMichael Clark <mjc@sifive.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
[PMM: Use qemu_tolower() rather than tolower()]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Add CPU state header, CPU definitions and initialization routines
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Signed-off-by: NSagar Karandikar <sagark@eecs.berkeley.edu>
Signed-off-by: NMichael Clark <mjc@sifive.com>