target/riscv: Remove ifndef CONFIG_USER_ONLY from cpu_cfg.h

target/riscv: Remove ifndef CONFIG_USER_ONLY from cpu_cfg.h

While RISCVCPUConfig.satp_mode is unused for user-only,
this header is used from disas/riscv.h, whose users are
only built once.  The savings of 4 bytes isn't worth it.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>