broadband-modem-qmi: enable/disable messaging AT unsolicited events too
Following earlier discussions on Matrix, this MR cherry-picks 9007d799 to the current stable branch, as it's a significant improvement for Librem 5 users.
Tested to work as expected on my own L5 (and maybe other ones as it's applied on top of 1.20.6 in Debian).
Edited by Arnaud Ferraris