coresight: Interpret ETMv4 config with ATTR_CFG_GET_FLD()

coresight: Interpret ETMv4 config with ATTR_CFG_GET_FLD()

Remove hard coded bitfield extractions and shifts and replace with
ATTR_CFG_GET_FLD().

ETM4_CFG_BIT_BB was defined to give the register bit positions to
userspace, TRCCONFIGR_BB should be used in the kernel so replace it.

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-v8-9-4d319764cc58@linaro.org