inpcb: remove extraneous check in inp_next()

[glebius]

Summary

The condition of the embracing for(;;) loop is the same.

[pouria]

sys/netinet/in_pcb.c

1601

Is it possible for inp to become NULL here first, and then for the for loop to attempt to update inp by assigning II_LIST_NEXT(**NULL**, hash) here?

[pouria]

sys/netinet/in_pcb.c

1601

I mean, theorically, for loop will update the variable first and then it will test its condition.
I don't think if II_LIST_NEXT can tolerate NULL input as its argument.
since it'll call the CK_LIST_NEXT macro and it will dereference inp to find its next element: &(NULL)->field.cle_next

[glebius]

Today was my turn to be stupid :) See 430df2abee9049c2e4773704190a9f0d1779ff10