- Remove sync from msgrng_send, sync needs to be called just once before
sending.
- Fix retry logic - don't reload registers when retrying in message_send,
also fix check for send pending fail.
- remove unused message_send_block_fast()
- merge message_receive_fast() to message_receive
- style(9) fixes, and comments
- rge and nlge updated for the sys/mips/rmi/msgring.h changes