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As we cannot have an exclusive stream set if the perf has not been
initialized, we only need to check for that exclusive stream.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170810175743.25401-3-chris@chris-wilson.co.uk

Reviewed-by: Matthew Auld <matthew.auld@intel.com>