coresight: Refactor driver data allocation

The driver data no longer needs to be allocated separately in the static
and dynamic probes. Moved the allocation into the low-level functions to
avoid code duplication.

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Tested-by: James Clark <james.clark@linaro.org>
Signed-off-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250731-arm_cs_fix_clock_v4-v6-8-1dfe10bb3f6f@arm.com