ASoC: mediatek: Fix unbalanced calls to runtime suspend/resume

This adds call to runtime suspend in dev remove. It fixs the problem that
suspend is not called in the case of CONFIG_PM=n. It also fixs build
warning when CONFIG_PM=n.

Signed-off-by: Koro Chen <koro.chen@mediatek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>