drm/exynos: use pm_runtime_resume_and_get()

Use pm_runtime_resume_and_get() instead of pm_runtime_get_sync()
to deal with usage counter. pm_runtime_get_sync() increases the
usage counter even when it failed, which makes callers to forget
to decrease the usage counter and resulted in reference leak.

pm_runtime_resume_and_get() function decreases the usage counter
when it failed internally so it can avoid the reference leak.

Changelog v1:
- Fix an build error reported by kernel test robot of Intel.

Signed-off-by: Inki Dae <inki.dae@samsung.com>
Reported-by: kernel test robot <lkp@intel.com>