ftrace/x86: Use asm/kprobes.h instead of linux/kprobes.h

If CONFIG_KPROBES is not set, then linux/kprobes.h will not include
asm/kprobes.h needed by x86/ftrace.c for the BREAKPOINT macro.

The x86/ftrace.c file should just include asm/kprobes.h as it does not
need the rest of kprobes.
Reported-by: NIngo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

arch/x86/kernel/ftrace.c

@@ -20,11 +20,11 @@
 #include <linux/init.h>
 #include <linux/list.h>
 #include <linux/module.h>
-#include <linux/kprobes.h>
 
 #include <trace/syscall.h>
 
 #include <asm/cacheflush.h>
+#include <asm/kprobes.h>
 #include <asm/ftrace.h>
 #include <asm/nops.h>