PNP: check for conflicts with all resources, not just earlier ones

This patch removes a use of "idx" in pnp_check_port() and similar
functions, in preparation for replacing idx with a pointer to the
resource itself.

I split this out because it changes the behavior slightly: we used
to check for conflicts only with earlier resources, e.g., we checked
resource 2 against resources 0 and 1 but not against 3, 4, etc.  Now
we will check against all resources except 2.

Since resources are assigned in ascending order, the old behavior
was probably safe, but I don't like to depend on that ordering.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Acked-By: Rene Herman <rene.herman@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>