PSA PAKE: define size macros as 0
PSA PAKE: define size macros as 0

Define the size macros to 0 rather than empty. That will lead to fewer
weird errors when we start implementing.

Signed-off-by: Janos Follath <b175c17abe0474719672be1367bb75ee28bd5c71@arm.com>

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