drm/i915/gvt: fix a bounds check in ring_id_to_context_switch_event()

There are two bugs here.  The && should be || and the > is off by one so
it should be >= ARRAY_SIZE().

Fixes: 8453d674 ("drm/i915/gvt: vGPU execlist virtualization")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>