wlcore: sdio: drop kfree for memory allocated with devm_kzalloc

It's not necessary to free memory allocated with devm_kzalloc
and using kfree leads to a double free.

Fixes: d776fc86 ("wlcore: sdio: Populate config firmware data")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>