RISC-V: defconfig: Drop redundant SBI HVC and earlycon

As of 3938d5a2 ("riscv: default to CONFIG_RISCV_SBI_V01=n") we no
longer default to enabling SBI-0.1 support, so these dependent configs
no longer have any effect.  Remove them to avoid clutter.

Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>