riscv: default to CONFIG_RISCV_SBI_V01=n

The SBI 0.1 specification is obsolete. The current version is 0.3.
Hence we should not rely by default on SBI 0.1 being implemented.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>