x86: Check PIRQ routing table sanity in the F segment

Previously the PIRQ routing table sanity check was performed against
the original table provided by the platform codes. Now we switch to
check its sanity on the final table in the F segment as this one is
the one seen by the OS.

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