[display] Do not repeatedly warn about scheduler change failures
[display] Do not repeatedly warn about scheduler change failures

While mce is adjusting display brightness, it temporarily boosts its
scheduling priority to increase chances of smooth animation sequence.
If that should fail, it is not fatal and repeated journal spamming can
only make timing errors more pronounced.

Log scheduler adjustment errors only once.

Signed-off-by: Simo Piiroinen <6d5e5360bed3d486f7d9fb26b0f737f7d4fd45ee@jollamobile.com>

spiiroin/mce,spiiroin/mce,spiiroin/mce,spiiroin/mce