feat(cert-create): add new option for CCA NV ctr

Extends cert_create tool with a new option for CCA NV
counter: ccafw_nvctr.

And changes the non-volatile counter used to protect
the CCA Content Certificate from the Trusted FW NV counter
to the CCA FW NV counter in the CCA CoT description.

Change-Id: I27f3ab2e25809f0dcc56fa05e5c3a25a2e861ef6
Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>