coresight: Interpret perf config with ATTR_CFG_GET_FLD()

coresight: Interpret perf config with ATTR_CFG_GET_FLD()

The "config:" string construction in format_attr_contextid_show() can be
removed because it either showed the existing context1 or context2
formats which have already been generated, so can be called themselves.

The other conversions are straightforward replacements.

Tested-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20251128-james-cs-syncfreq-v8-8-4d319764cc58@linaro.org