Change in coreboot[master]: sb,soc/intel: Use register_new_ioapic_gsi0()

[Angel Pons (Code Review)]

Attention is currently required from: Mariusz Szafrański, Suresh Bellampalli, Vanessa Eusebio, Michal Motyl, Kyösti Mälkki, Patrick Rudolph.
Angel Pons has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/55314 )

Change subject: sb,soc/intel: Use register_new_ioapic_gsi0()
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Patch Set 3: Code-Review+2

(1 comment)

File src/southbridge/intel/i82870/ioapic.c:

https://review.coreboot.org/c/coreboot/+/55314/comment/171cb4ca_f6ff6fe8 
PS3, Line 38: 	register_new_ioapic((void *)memoryBase);
I'd either do this on a separate commit, or at least mention that `register_new_ioapic` is used here in the commit message body.