riscv: don't look at SUM when accessing memory from a debugger context

riscv: don't look at SUM when accessing memory from a debugger context

Previously the qemu monitor and gdbstub looked at SUM and refused to
perform accesses to user memory if it is off, which was an impediment to
debugging.

Signed-off-by: Jade Fink <qemu@jade.fyi>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20210406113109.1031033-1-qemu@jade.fyi
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>