target/riscv: rvv: Check single width operator for vfncvt.rod.f.f.w

target/riscv: rvv: Check single width operator for vfncvt.rod.f.f.w

The opfv_narrow_check needs to check the single width float operator by
require_rvf.

Signed-off-by: Max Chou <max.chou@sifive.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Cc: qemu-stable <qemu-stable@nongnu.org>
Message-ID: <20240322092600.1198921-4-max.chou@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
(cherry picked from commit 692f33a3abcaae789b08623e7cbdffcd2c738c89)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>