net/smc: separate function for link initialization

Move the initialization of a new link into its own function, separate
from smc_lgr_create, to allow more than one link per link group.
Do an extra check if the IB device initialization was successful, and
reset the link state if any error occurs during smcr_link_init().
And rename two existing functions to use the prefix smcr_ to indicate
that they belong to the SMC-R code path.

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