COSE: Switch tests over to upstream t_cose

Switch from TF-M's t_cose library fork to the upstream repo
being downloaded from https://github.com/laurencelundblade/t_cose.

Change-Id: I9e2a859c67e902c6ecc1dc5ab996241e3d33e4ab
Signed-off-by: Adam Kulesza <adam.kulesza@arm.com>
Signed-off-by: David Vincze <david.vincze@arm.com>
Signed-off-by: Tamas Ban <tamas.ban@arm.com>
17 files changed