linux-firmware: update Marvell PCIe/USB 8897-B0 firmware combo image

WLAN (PCIe) firmware version: 15.68.4.p22
Bluetooth (USB) firmware version: 15.28.4.p22

The combo image will be downloaded through WLAN only.
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: Frank Huang <frankh@marvell.com>

WHENCE

@@ -736,7 +736,7 @@ File: mrvl/usb8797_uapsta.bin
 Version: 14.68.29.p26
 
 File: mrvl/pcie8897_uapsta.bin
-Version: 15.69.2.p11
+Version: 15.68.4.p22
 
 Licence: Redistributable. See LICENCE.Marvell for details.  Originates from
 http://git.marvell.com/?p=mwifiex-firmware.git