ci: fix QCBOR clone path

Update the QCBOR cloning path to create its instance within
the TF-A source code repository.

Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
Change-Id: I9b9505f7362fabf76ce6c24415eaec98b48e79f3
1 file changed