wifi: wl12xx: Drop if with an always false condition

The remove callback is only called after probe completed successfully.
In this case platform_set_drvdata() was called with a non-NULL argument
(in wlcore_probe()) and so wl is never NULL.

This is a preparation for making platform remove callbacks return void.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220715224619.ht7bbzzrmysielm7@pengutronix.de