coresight: etm4x: core: Remove redundant check of attr

coresight: etm4x: core: Remove redundant check of attr

"attr" is checked by perf framework, so remove the redundant check in
etm4_parse_event_config().

Link: https://lore.kernel.org/r/1620912469-52222-4-git-send-email-liuqi115@huawei.com
Signed-off-by: Junhao He <hejunhao2@hisilicon.com>
Signed-off-by: Qi Liu <liuqi115@huawei.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20210614175901.532683-5-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>