mwifiex: add default setting for pcie firmware download

This patch adds default setting for pcie firmware download name in
case that there are newer chipset version.

Signed-off-by: Shengzhen Li <szli@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>