drm/i915: selftest_lrc: Check the correct variable

We should check "request[n]" instead of just "request".

Fixes: 78e41ddd ("drm/i915: Apply an execution_mask to the virtual_engine")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190529110355.GA19119@mwanda