target/riscv: Fix pmp.h/cpu.h circular inclusion

pmp.h is only needed and included for system mode, however relevant macros (MAX_RISCV_PMPS, OLD_MAX_RISCV_PMPS, MIN_RISCV_PMP_GRANULARITY) are required unconditionally by cpu.c, and so are defined in cpu.h. pmp.h then defines pmp_table_t depending on these macros and so requires cpu.h, and cpu.h in turn uses pmp_table_t resulting in circular inclusion. Move PMP macros to pmp.h and only expose PMP properties in system mode. Signed-off-by: Anton Johansson <anjo@rev.ng> Reviewed-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Reviewed-by: Alistair Francis <alistair.francis@wdc.com> Message-ID: <20260520125406.28693-28-anjo@rev.ng> Signed-off-by: Alistair Francis <alistair.francis@wdc.com>