drm/exynos: fix ref count leak in mic_pre_enable

[ Upstream commit d4f5a095daf0d25f0b385e1ef26338608433a4c5 ]

in mic_pre_enable, pm_runtime_get_sync is called which
increments the counter even in case of failure, leading to incorrect
ref count. In case of failure, decrement the ref count before returning.

Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>