pidfd: prevent a kernel-doc warning

Change the comment to match the function name that the SYSCALL_DEFINE()
macros generate to prevent a kernel-doc warning.

kernel/pid.c:628: warning: expecting prototype for pidfd_open(). Prototype was for sys_pidfd_open() instead

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Randy Dunlap <[email protected]>
Cc: Christian Brauner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: rddunlap

kernel/pid.c

@@ -609,7 +609,7 @@ int pidfd_create(struct pid *pid, unsigned int flags)
 }
 
 /**
- * pidfd_open() - Open new pid file descriptor.
+ * sys_pidfd_open() - Open new pid file descriptor.
  *
  * @pid:   pid for which to retrieve a pidfd
  * @flags: flags to pass