kprobes: update jprobe_example.c for do_fork() change

In commit e80d6661 "flagday: kill pt_regs argument of do_fork()", the
arguments to do_fork() changed.

The example code in jprobe_example.c was not updated to match, so the
arguments inside the jprobe handler do not match reality.

Fix it by updating the arguments to match do_fork(). While we're at it
use pr_info() for brevity, and print stack_start as well for interest.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

samples/kprobes/jprobe_example.c

@@ -24,12 +24,11 @@
 
 /* Proxy routine having the same arguments as actual do_fork() routine */
 static long jdo_fork(unsigned long clone_flags, unsigned long stack_start,
-	      struct pt_regs *regs, unsigned long stack_size,
-	      int __user *parent_tidptr, int __user *child_tidptr)
+	      unsigned long stack_size, int __user *parent_tidptr,
+	      int __user *child_tidptr)
 {
-	printk(KERN_INFO "jprobe: clone_flags = 0x%lx, stack_size = 0x%lx,"
-			" regs = 0x%p\n",
-	       clone_flags, stack_size, regs);
+	pr_info("jprobe: clone_flags = 0x%lx, stack_start = 0x%lx "
+		"stack_size = 0x%lx\n", clone_flags, stack_start, stack_size);
 
 	/* Always end with a call to jprobe_return(). */
 	jprobe_return();