test: synchronizers: use thread_id instead of cpu_id to detect slow thread
test: synchronizers: use thread_id instead of cpu_id to detect slow thread

The test assumes that cpu_id ranges from 0 to n CPU - 1 which is not necessary true on all archs.
Meanwhile thread ids are always ranging from 0 to N (0 here is for the main test thread)

Signed-off-by: Nicolas Morey-Chaisemartin <7188b998d7bb37a035517aa285fa3f5a95344e80@kalray.eu>
Reviewed-by: Bill Fischofer <52f3c909d51cc5d355a68a403df6906b3c1a8f83@linaro.org>
Signed-off-by: Maxim Uvarov <db4d16e02ae2d7493db430203537da8b2e34f290@linaro.org>

mike-holmes-linaro/odp,dkrot/odp,kalray/odp-mppa,ravineet-singh/odp,rsalveti/odp,kalray/odp-mppa,nmorey/odp,erachmi/odp,ravineet-singh/odp,ravineet-singh/odp,mike-holmes-linaro/odp,mike-holmes-linaro/odp,kalray/odp-mppa,dkrot/odp,kalray/odp-mppa,erachmi/odp,nmorey/odp,erachmi/odp,rsalveti/odp,rsalveti/odp,rsalveti/odp,dkrot/odp,dkrot/odp,kalray/odp-mppa,rsalveti/odp,mike-holmes-linaro/odp,nmorey/odp,kalray/odp-mppa,erachmi/odp,ravineet-singh/odp,nmorey/odp,kalray/odp-mppa