coresight: Store pointers to connections rather than an array of them

This will allow the same connection object to be referenced via the
input connection list in a later commit rather than duplicating them.

Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230425143542.2305069-8-james.clark@arm.com