cert_create: improve command line argument check
Juan Castillo authored
The certificate generation tool currently checks if all command
line options required to create all certificates in the CoT have
been specified. This prevents using the tool to create individual
certificates when the whole CoT is not required.

This patch improves the checking function so only those options
required by the certificates specified in the command line are
verified.

Change-Id: I2c426a8e2e2dec85b15f2d98fd4ba949c1aed385
dfc90e26