cpu/x86/lapic: Replace LOCAL_APIC_ADDR references

Note that there are assumptions about LAPIC MMIO location
in both AMD and Intel sources in coreboot proper.

Change-Id: I2c668f5f9b93d170351c00d77d003c230900e0b4
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55194
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/arch/x86/cpu.c

@@ -340,8 +340,3 @@ int cpu_index(void)
 	}
 	return -1;
 }
-
-uintptr_t cpu_get_lapic_addr(void)
-{
-	return LOCAL_APIC_ADDR;
-}