x86: apl: Use read-only SPL and new of-platdata

With Apollo Lake, SPL is placed in read-only memory. Set this new option
so that OF_PLATDATA_INST can be used.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/cpu/apollolake/Kconfig b/arch/x86/cpu/apollolake/Kconfig
index 590fe31..b3ce053 100644
--- a/arch/x86/cpu/apollolake/Kconfig
+++ b/arch/x86/cpu/apollolake/Kconfig
@@ -21,6 +21,8 @@
 	select INTEL_GMA_SWSMISCI
 	select ACPI_GNVS_EXTERNAL
 	select TPL_OF_PLATDATA_PARENT
+	select TPL_OF_PLATDATA_INST
+	select TPL_READ_ONLY
 	imply ENABLE_MRC_CACHE
 	imply AHCI_PCI
 	imply SCSI