psa: Decrement slot access count when finalizing key creation
psa: Decrement slot access count when finalizing key creation

Decrement the slot access count in psa_finish_key_creation()
when the finalization succeeds instead of in functions calling
psa_finish_key_creation(). That way the decrementation cannot
be forgotten and it reduces the code size.

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

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