docs(threat_model): mark power analysis threats out-of-scope

Exclude the threat of power analysis side-channel attacks
from consideration in the TF-A generic threat model.

Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
Change-Id: I5b245f33609fe8948e473ce4484898db5ff8db4d
1 file changed