target/riscv: rvv-1.0: Add Zve64f support for scalar fp insns

target/riscv: rvv-1.0: Add Zve64f support for scalar fp insns

Zve64f extension requires the scalar processor to implement the F
extension and implement all vector floating-point instructions for
floating-point operands with EEW=32 (i.e., no widening floating-point
operations).

Signed-off-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20220118014522.13613-7-frank.chang@sifive.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>