target/riscv: Fix the mepc when sspopchk triggers the exception

target/riscv: Fix the mepc when sspopchk triggers the exception

When sspopchk is in the middle of TB and triggers the SW check
exception, it should update PC from gen_update_pc(). If not, RISC-V mepc
CSR will get wrong PC address which is still at the start of TB.

Signed-off-by: Jim Shu <jim.shu@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20250924074818.230010-2-jim.shu@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
(cherry picked from commit c851052a77fd79300708df2070297b5428b4be8d)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>