rsi: fix error code in rsi_load_9116_firmware()

This code returns success if the kmemdup() fails, but obviously it
should return -ENOMEM instead.

Fixes: e5a1ecc9 ("rsi: add firmware loading for 9116 device")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210805103746.GA26417@kili