hw/riscv: remove 'fdt' param from riscv_setup_rom_reset_vec()

hw/riscv: remove 'fdt' param from riscv_setup_rom_reset_vec()

The 'fdt' param is not being used in riscv_setup_rom_reset_vec().
Simplify the API by removing it. While we're at it, remove the redundant
'return' statement at the end of function.

Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Alistair Francis <alistair.francis@wdc.com>
Cc: Bin Meng <bin.meng@windriver.com>
Cc: Vijai Kumar K <vijai@behindbytes.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20220728181926.2123771-1-danielhb413@gmail.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>