IB/ipath: Port config has on-chip effects for 7220

The number of configured ports for the 7220 changes the number of eager
TIDs available per port, for all but port 0 (kernel port) which remains
constant, so add a field to give port0 count separate from the portdata
structure.

Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>