target/riscv: Set mstatus_hs.[SD|FS] bits if Clean and V=1 in mark_fs_dirty()

target/riscv: Set mstatus_hs.[SD|FS] bits if Clean and V=1 in mark_fs_dirty()

When V=1, both vsstauts.FS and HS-level sstatus.FS are in effect.
Modifying the floating-point state when V=1 causes both fields to
be set to 3 (Dirty).

However, it's possible that HS-level sstatus.FS is Clean and VS-level
vsstatus.FS is Dirty at the time mark_fs_dirty() is called when V=1.
We can't early return for this case because we still need to set
sstatus.FS to Dirty according to spec.

Signed-off-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Vincent Chen <vincent.chen@sifive.com>
Tested-by: Vincent Chen <vincent.chen@sifive.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20210921020234.123448-1-frank.chang@sifive.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>