mwifiex: Fix firmware filename for sd8997 chipset

mwifiex: Fix firmware filename for sd8997 chipset

[ Upstream commit 2e1fcac52a9ea53e5a13a585d48a29a0fb4a9daf ]

Firmware for sd8997 chipset is distributed by Marvell package and also as
part of the linux-firmware repository in filename sdsd8997_combo_v4.bin.

This patch fixes mwifiex driver to load correct firmware file for sd8997.

Fixes: 6d85ef00d9dfe ("mwifiex: add support for 8997 chipset")
Signed-off-by: Pali Rohár <pali@kernel.org>
Acked-by: Ganapathi Bhat <ganapathi.bhat@nxp.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>