nano_fifo: Fix problem with nano_fifo and timeouts

Fixes a problem where the nanokernel FIFO state information could get
out of sync due to a timeout.

The nanokernel FIFO structure nano_fifo now maintains two separate
queues: one for waiting fibers and the other for posted data. This
permits the safe and independent querying of the queues as needed
when getting and/or putting data from/on the nanokernel FIFO.

Change-Id: Ifbcb5004558b06fc55cad2a955f5be20e716b392
Signed-off-by: Peter Mitsis <peter.mitsis@windriver.com>