[CORE] vmm_devemu: Halt VCPU when read/write/ioread/iowrite fails

If read/write/ioread/iowrite fails then it implies that VCPU
misbehaved and tried to access invalid guest address.

Currently, we rely on arch code to handle this failure and hope
that arch code will halt the VCPU.

This patch enforces VCPU halt upon read/write/ioread/iowrite
failure from core code itself so that arch code does not have
to explicity halt VCPU.

Signed-off-by: Anup Patel <anup@brainfault.org>