[NXP SE05x] Remove the logic to track signature calls for attestation

[sujaygkulkarni-nxp]

Reproduction steps

1. Code inspection of examples/platform/nxp/se05x/DeviceAttestationSe05xCredsExample_v2.cpp file.
static variable 'sign_cert_decl_attest' is used for tracking signature calls for nocsr and certificate declaration.
Todo - Change the implementation to remove this tracking logic 

2. Use size() operator to get the length in tlv parsing

Platform

other

Platform Version(s)

N/A

Type

Platform validated

(Optional) If manually tested please explain why this is only manually tested

No response

Anything else?

No response