coresight: Define format attributes with GEN_PMU_FORMAT_ATTR()

coresight: Define format attributes with GEN_PMU_FORMAT_ATTR()

This allows us to define and consume them in a unified way in later
commits.

A lot of the existing code has open coded bit shifts or direct usage of
whole config values which is error prone and hides which bits are in use
and which are free.

Reviewed-by: Leo Yan <leo.yan@arm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
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-v8-5-4d319764cc58@linaro.org