net/core: Document all dev_ioctl() arguments

This patch avoids that the following warnings are reported when building
with W=1:

net/core/dev_ioctl.c:378: warning: Function parameter or member 'ifr' not described in 'dev_ioctl'
net/core/dev_ioctl.c:378: warning: Function parameter or member 'need_copyout' not described in 'dev_ioctl'
net/core/dev_ioctl.c:378: warning: Excess function parameter 'arg' description in 'dev_ioctl'

Cc: Al Viro <viro@zeniv.linux.org.uk>
Fixes: 44c02a2c3d ("dev_ioctl(): move copyin/copyout to callers") # v4.16.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/dev_ioctl.c

@@ -366,7 +366,8 @@ EXPORT_SYMBOL(dev_load);
  *	dev_ioctl	-	network device ioctl
  *	@net: the applicable net namespace
  *	@cmd: command to issue
- *	@arg: pointer to a struct ifreq in user space
+ *	@ifr: pointer to a struct ifreq in user space
+ *	@need_copyout: whether or not copy_to_user() should be called
  *
  *	Issue ioctl functions to devices. This is normally called by the
  *	user space syscall interfaces but can sometimes be useful for