Merge branch 'net-usb-qmi_wwan-new-mux_id-sysfs-file'

Merge branch 'net-usb-qmi_wwan-new-mux_id-sysfs-file'

Daniele Palmas says:

====================
net: usb: qmi_wwan: new mux_id sysfs file

this patch series add a sysfs file to let userspace know which mux
id has been used to create a qmimux network interface.

I'm aware that adding new sysfs files is not usually the right path,
but my understanding is that this piece of information can't be
retrieved in any other way and its absence restricts how
userspace application (e.g. like libqmi) can take advantage of the
qmimux implementation in qmi_wwan.
====================

Link: https://lore.kernel.org/r/20210127153433.12237-1-dnlplm@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>