backends/drm: fix mode updates
Commit 1: prevent unnecessary modesets
Commit 2: let DrmGpu
handle mode changes, doing atomic tests directly doesn't make sense here and can cause crashes. Should fix BUG: 450804
Edited by Xaver Hugl
Commit 1: prevent unnecessary modesets
Commit 2: let DrmGpu
handle mode changes, doing atomic tests directly doesn't make sense here and can cause crashes. Should fix BUG: 450804