drm/etnaviv: fix ref count leak via pm_runtime_get_sync

drm/etnaviv: fix ref count leak via pm_runtime_get_sync

[ Upstream commit c5d5a32ead1e3a61a07a1e59eb52a53e4a6b2a7f ]

in etnaviv_gpu_submit, etnaviv_gpu_recover_hang, etnaviv_gpu_debugfs,
and etnaviv_gpu_init the call to pm_runtime_get_sync 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: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>