[ Upstream commit 61356088ace1866a847a727d4d40da7bf00b67fc ]

The QMAP code in the qmi_wwan driver is based on the CodeAurora GobiNet
driver which does not process QMAP padding in the RX path correctly.
Add support for QMAP padding to qmimux_rx_fixup() according to the
description of the rmnet driver.

Fixes: c6adf779 ("net: usb: qmi_wwan: add qmap mux protocol support")
Cc: Daniele Palmas <dnlplm@gmail.com>
Signed-off-by: NReinhard Speyerer <rspmn@arcor.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NSasha Levin <sashal@kernel.org>