x86: Allow compiling out realmode/bios code

We don't want this for coreboot, so provide a way of compiling it out.

Signed-off-by: Gabe Black <gabeblack@chromium.org>
Signed-off-by: Stefan Reinauer <reinauer@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/README b/README
index b9a3685..ed7d270 100644
--- a/README
+++ b/README
@@ -3668,6 +3668,12 @@
 		If defined, the x86 reset vector code is excluded. You will need
 		to do this when U-Boot is running from Coreboot.
 
+- CONFIG_X86_NO_REAL_MODE
+		If defined, x86 real mode code is omitted. This assumes a
+		32-bit environment where such code is not needed. You will
+		need to do this when U-Boot is running from Coreboot.
+
+
 Freescale QE/FMAN Firmware Support:
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