Fix doxygen for new x509 structures
Fix doxygen for new x509 structures

The documentation for some new structures and members was only a C style
comment and wasn't picked up by doxygen. This commit adds the missing
asterisks.

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