ssl_tls12_client.c: Simplify TLS version in encrypted PMS
ssl_tls12_client.c: Simplify TLS version in encrypted PMS

This can only be TLS 1.2 now in this structure and when
adding support for TLS 1.2 or 1.3 version negotiation
the highest configured version can be TLS 1.3.

Signed-off-by: Ronald Cron <b35ff5b7ca26c4ae9b66b92f2cf34224c8e26b08@arm.com>

Mbed-TLS/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls