staging: wimax: add a blank line after declaration in op-rfkill.c

staging: wimax: add a blank line after declaration in op-rfkill.c

This commit fixes the following checkpatch.pl warning:

WARNING: Missing a blank line after declarations
+	struct device *dev = wimax_dev_to_dev(wimax_dev);
+	d_fnstart(3, dev, "(wimax_dev %p)\n", wimax_dev);

Signed-off-by: Gabriele Modena <gabriele.modena@gmail.com>
Link: https://lore.kernel.org/r/1ee3795245816a81609749c82c3d369ea0cbf466.1615652628.git.gabriele.modena@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>