caif: fix endian conversion in cffrml_transmit()

The "tmp" variable here is used to store the result of cpu_to_le16()
so it should be an __le16 instead of an int.  We want the high bits
set and the current code works on little endian systems but not on
big endian systems.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>