dev_ioctl: fix a W=1 warning

This fixes the following warning when compiled with GCC 12.2.0 and W=1.

net/core/dev_ioctl.c:475: warning: Function parameter or member 'data'
not described in 'dev_ioctl'

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>