coresight: etm4x: Drop pid argument from etm4_probe()

Coresight device pid can be retrieved from its iomem base address, which is
stored in 'struct etm4x_drvdata'. This drops pid argument from etm4_probe()
and 'struct etm4_init_arg'. Instead etm4_check_arch_features() derives the
coresight device pid with a new helper coresight_get_pid(), right before it
is consumed in etm4_hisi_match_pid().

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>