drm/amdgpu: Fix validating flush_gpu_tlb_pasid()

When a function holds a lock and we return without unlocking it,
it deadlocks the kernel. We should always unlock before returning.

This commit fixes suspend/resume on SI.
Tested on two Tahiti GPUs: FirePro W9000 and R9 280X.

Fixes: f4db991 ("drm/amdgpu: validate the flush_gpu_tlb_pasid()")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202601190121.z9C0uml5-lkp@intel.com/
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Prike Liang <Prike.Liang@amd.com>
Reviewed-by: Prike Liang <Prike.Liang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit e3a6eff)

Author: Timur Kristóf

drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c

@@ -733,8 +733,10 @@ int amdgpu_gmc_flush_gpu_tlb_pasid(struct amdgpu_device *adev, uint16_t pasid,
 
 	if (!adev->gmc.flush_pasid_uses_kiq || !ring->sched.ready) {
 
-		if (!adev->gmc.gmc_funcs->flush_gpu_tlb_pasid)
-			return 0;
+		if (!adev->gmc.gmc_funcs->flush_gpu_tlb_pasid) {
+			r = 0;
+			goto error_unlock_reset;
+		}
 
 		if (adev->gmc.flush_tlb_needs_extra_type_2)
 			adev->gmc.gmc_funcs->flush_gpu_tlb_pasid(adev, pasid,