net/smc: nonblocking connect rework

For nonblocking sockets move the kernel_connect() from the connect
worker into the initial smc_connect part to return kernel_connect()
errors other than -EINPROGRESS to user space.

Reviewed-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>