Update cipher.h
Update cipher.h

Minor documentation improvements:
*Standardized file brief description.
*Separated return statements.
*Reordered tags within documentation blocks so that params and returns are last in block.
*Added missing documentation in lines 99-159 (values in enums) - need to be verified.
*lines 79+80 and 97+98 - verify descriptions + what is the difference here between none and null?
*lines 177-187 - seems to be an enum without a name?
NXPmicro/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,NXPmicro/mbedtls,ARMmbed/mbedtls,NXPmicro/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,NXPmicro/mbedtls,Mbed-TLS/mbedtls