target/riscv: Fix VS mode interrupts forwarding.

target/riscv: Fix VS mode interrupts forwarding.

Currently riscv_cpu_local_irq_pending is used to find out pending
interrupt and VS mode interrupts are being shifted to represent
S mode interrupts in this function. So when the cause returned by
this function is passed to riscv_cpu_do_interrupt to actually
forward the interrupt, the VS mode forwarding check does not work
as intended and interrupt is actually forwarded to hypervisor. This
patch fixes this issue.

Signed-off-by: Rajnesh Kanwal <rajnesh.kanwal49@gmail.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>