net: qrtr: haven: Add fragmentation support

Clients may need to send packets larger than the physical transport
allows. Add fragmantation support into the transport layer so packets
larger than the shared memory fifo can be sent.

This change increases the max packet size to 64k. The send function
will now block until the entire packet has been sent across the shared
fifo.

Change-Id: I4e36671fbdd6a4de57abdb3d49b3757d8ceb0233
Signed-off-by: Chris Lew <clew@codeaurora.org>