net/smc: consolidate function parameters

During initialization of an SMC socket a lot of function parameters need
to get passed down the function call path. Consolidate the parameters
in a helper struct so there are less enough parameters to get all passed
by register.

Signed-off-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>