arch/x86/gdt: Correct format of multi-line comment

Change-Id: I87148315cdf7e420eac2f3f680251f8e963a9707
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: https://review.coreboot.org/21956
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Sumeet R Pawnikar <sumeet.r.pawnikar@intel.com>

src/arch/x86/gdt.c

@@ -30,7 +30,8 @@ struct gdtarg {
 #endif
 } __packed;
 
-/* Copy GDT to new location and reload it.
+/*
+ * Copy GDT to new location and reload it.
  * FIXME: We only do this for BSP CPU.
  */
 static void move_gdt(int is_recovery)