x86/syscall/32: Add comment to conditional

Add a CONFIG_X86_FRED comment, since this conditional is nested.

Suggested-by: Sohil Mehta <[email protected]>
Signed-off-by: Brian Gerst <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Reviewed-by: Sohil Mehta <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Brian Gerst

arch/x86/entry/syscall_32.c

@@ -238,7 +238,8 @@ DEFINE_FREDENTRY_RAW(int80_emulation)
 	instrumentation_end();
 	syscall_exit_to_user_mode(regs);
 }
-#endif
+#endif /* CONFIG_X86_FRED */
+
 #else /* CONFIG_IA32_EMULATION */
 
 /* Handles int $0x80 on a 32bit kernel */