drm/etnaviv: Warn when GPU doesn't idle fast enough

If the GPU isn't idle after signalling pm_runtime_mark_last_busy() plus
waiting for the autosuspend delay there's likely something wrong with
the way we check idleness so warn about that.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
2 jobs for mrs/gpu-idle in 41 minutes and 38 seconds
Status Job ID Name Coverage
  Build
passed #252143
librem5
build:aarch64

00:13:27

passed #252144
librem5:arm64
build:deb

00:41:36