[IA64] Delete iosapic_free_rte()

>   arch/ia64/kernel/iosapic.c:597: warning: 'iosapic_free_rte' defined but not used
>
> This isn't spurious, the only call to iosapic_free_rte() has been removed, but there
> is still a call to iosapic_alloc_rte() ... which means we must have a memory leak.

I did it on purpose (and gave the warning a miss...) and I consider
iosapic_free_rte() is no longer needed.

I decided to remain iosapic_rte_info to keep gsi-to-irq binding
after device disable. Indeed it needs some extra memory, but it
is only "sizeof(iosapic_rte_info) * <the number of removed devices>"
bytes and has no memory leak becasue re-enabled devices use the
iosapic_rte_info which they used before disabling.

Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>