soc/intel/apl: Fix programming temporary MTRR on GLK

Programming MTRR happens later in the
CONFIG_SOC_INTEL_COMMON_BLOCK_CPU_MPINIT codepath.
fast_spi_cache_bios_region() assumes an existing MTRR solution from
x86_setup_mtrrs_with_detect().

This fixes a problem introduced by 829e8e6 "soc/intel: Use common
codeflow for MP init".

Change-Id: I9b6130cf76317440ebe7a7a53e460e2b658d198e
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/73836
Reviewed-by: Sean Rhodes <sean@starlabs.systems>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/apollolake/cpu.c

@@ -268,6 +268,10 @@ void mp_init_cpus(struct bus *cpu_bus)
 	/* TODO: Handle mp_init_with_smm failure? */
 	mp_init_with_smm(cpu_bus, &mp_ops);
 
+	/* MTRR setup happens later, so we're done here. */
+	if (CONFIG(SOC_INTEL_COMMON_BLOCK_CPU_MPINIT))
+		return;
+
 	/* Temporarily cache the memory-mapped boot media. */
 	if (CONFIG(BOOT_DEVICE_MEMORY_MAPPED) &&
 		CONFIG(BOOT_DEVICE_SPI_FLASH))