broadband-modem-qmi: log reason of QMI port open failure
If ModemManager fails to open a QMI port with data format update, it retries without update. It would be useful to log the reason why the first try failed; for example on RHEL 7.6 ModemManager fails to write to sysfs due to SELinux. With this commit, the following message would be logged:
<debug> QMI port open operation finished
<debug> Couldn't open QMI port with data format update: Expected data
format not updated properly: Failed to open file
'/sys/class/net/wwp0s29u1u2i8/qmi/raw_ip' for R/W: Permission denied
<debug> Opening QMI device...
instead of just:
<debug> QMI port open operation finished
<debug> Opening QMI device...