linux-firmware: add Marvell USB8997 firmware image

WLAN (USB) firmware version: 16.68.1.p113.
Bluetooth (USB) firmware version: 16.26.1.p113.

Both WLAN and bluetooth are on USB interface.
The combo image will be downloaded through WLAN only.

Signed-off-by: Nishant Sarmukadam <nishants@marvell.com>
Signed-off-by: Ganapathi Bhat <gbhat@marvell.com>