cbfs: Use NO_XIP_EARLY_STAGES to decide if stage is XIP

Modern platforms like Apollolake do not use XIP for early stages. In
such cases, cbfs_prog_stage_load should check for NO_XIP_EARLY_STAGES
instead of relying on ARCH_X86 to decide if a stage is XIP.

Change-Id: I1729ce82b5f678ce8c37256090fcf353cc22b1ec
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/15045
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/Kconfig

@@ -204,8 +204,7 @@ config NO_XIP_EARLY_STAGES
 	default n if ARCH_X86
 	default y
 	help
-	  Identify if --xip parameter needs to be passed into cbfstool for early
-	  stages.
+	  Identify if early stages are eXecute-In-Place(XIP).
 
 config EARLY_CBMEM_INIT
 	def_bool !LATE_CBMEM_INIT