coresight: Fix ref leak when of_coresight_parse_endpoint() fails

coresight: Fix ref leak when of_coresight_parse_endpoint() fails

of_graph_get_next_endpoint() releases the reference to the previous
endpoint on each iteration, but when parsing fails the loop exits
early meaning the last reference is never dropped.

Fix it by dropping the refcount in the exit condition.

Fixes: d375b356e687 ("coresight: Fix support for sparsely populated ports")
Signed-off-by: James Clark <james.clark@arm.com>
Reported-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20240529133626.90080-1-james.clark@arm.com