Introduce function to indicate if record is fully processed
Introduce function to indicate if record is fully processed

This commit introduces a function ssl_record_is_in_progress()
to indicate if there is there is more data within the current
record to be processed. Further, it moves the corresponding
call from ssl_read_record_layer() to the parent function
mbedtls_ssl_read_record(). With this change, ssl_read_record_layer()
has the sole purpose of fetching and decoding a new record,
and hence this commit also renames it to ssl_get_next_record().

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