x86: remove SEGMENT_IS_FLAT_CODE

There are no users in the kernel.
Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/asm-x86/segment.h

@@ -131,9 +131,6 @@
  * Matching rules for certain types of segments.
  */
 
-/* Matches __KERNEL_CS and __USER_CS (they must be 2 entries apart) */
-#define SEGMENT_IS_FLAT_CODE(x)  (((x) & 0xec) == GDT_ENTRY_KERNEL_CS * 8)
-
 /* Matches PNP_CS32 and PNP_CS16 (they must be consecutive) */
 #define SEGMENT_IS_PNP_CODE(x)   (((x) & 0xf4) == GDT_ENTRY_PNPBIOS_BASE * 8)