net/smc: determine port attributes independent from pnet table

For SMC it is important to know the current port state of RoCE devices.
Monitoring port states has been triggered, when a RoCE device was added
to the pnet table. To support future alternatives to the pnet table the
monitoring of ports is made independent of the existence of a pnet table.
It starts once the smc_ib_device is established.

Due to this change smc_ib_remember_port_attr() is now a local function
and shuffling its location and the location of its used functions
makes any forward references obsolete.

And the duplicate SMC_MAX_PORTS definition is removed.

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