drm/exynos: fix runtime_pm fimd device state on probe

A call to pm_runtime_set_active() forces device to be at the active
state and skips calling its runtime suspend/resume callbacks. This
results in a freeze with a new power domain code based on gen_pd. Fimd
driver does all required runtime power management calls, so this
pm_runtime_set_active call is buggy. This patch removes it and corrects
clock management in probe function (clocks are now enabled by
pm_runtime_get_sync() call).

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>