target/riscv: Add 'P1P13' bit in SMSTATEEN0

target/riscv: Add 'P1P13' bit in SMSTATEEN0

Based on privilege 1.13 spec, there should be a bit56 for 'P1P13' in
mstateen0 that controls access to the hedeleg.

Signed-off-by: Fea.Wang <fea.wang@sifive.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Weiwei Li <liwei1518@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20240606135454.119186-4-fea.wang@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>