net/smc: remove unneeded include for smc.h

The only smc-related reference in net/sock.h is struct smc_hashinfo.
But just its address is refered to. Thus there is no need for the
include of net/smc.h. Remove it.

Suggested-by: Jakub Kicinski <jakub.kicinski@netronome.com>
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>