hw/riscv: sifive_u: Remove the riscv_ prefix of the soc* functions

hw/riscv: sifive_u: Remove the riscv_ prefix of the soc* functions

To keep consistency with the machine* functions, remove the riscv_
prefix of the soc* functions.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 1590072147-13035-1-git-send-email-bmeng.cn@gmail.com
Message-Id: <1590072147-13035-1-git-send-email-bmeng.cn@gmail.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>