x86: Reduce PIRQ routing table size

There is no need to populate multiple irq info entries with the same
bus number and device number, but with different interrupt pin. We
can use the same entry to store all the 4 interrupt pin (INT A/B/C/D)
routing information to reduce the whole PIRQ routing table size.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>