sb,soc/intel: Set IOAPIC redirection entry count

The number of redirection table entries (aka interrupt vectors) inside
an I/O APIC may depend of the SKU, with the related register being of
type read/write-once. Provide support utilities to either lock or set
this registers value.

Change-Id: I8da869ba390dd821b43032e4ccbc9291c39e6bab
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55289
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/src/southbridge/intel/ibexpeak/lpc.c b/src/southbridge/intel/ibexpeak/lpc.c
index c14c6a2..f1cf7a3 100644
--- a/src/southbridge/intel/ibexpeak/lpc.c
+++ b/src/southbridge/intel/ibexpeak/lpc.c
@@ -34,12 +34,10 @@
  */
 static void pch_enable_ioapic(struct device *dev)
 {
-	u32 reg32;
-
 	set_ioapic_id(VIO_APIC_VADDR, 0x01);
+
 	/* affirm full set of redirection table entries ("write once") */
-	reg32 = io_apic_read(VIO_APIC_VADDR, 0x01);
-	io_apic_write(VIO_APIC_VADDR, 0x01, reg32);
+	ioapic_lock_max_vectors(VIO_APIC_VADDR);
 }
 
 static void pch_enable_serial_irqs(struct device *dev)