drm/imagination: Use pvr_vm_context_get()

[ Upstream commit eb4accc ]

I missed this open-coded kref_get() while trying to debug a refcount
bug, so let's use the helper function here to avoid that waste of time
again in the future.

Fixes: ff5f643 ("drm/imagination: Add GEM and VM related code")
Reviewed-by: Frank Binns <frank.binns@imgtec.com>
Link: https://patchwork.freedesktop.org/patch/msgid/8616641d-6005-4b25-bc0a-0b53985a0e08@imgtec.com
Signed-off-by: Matt Coster <matt.coster@imgtec.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: MTCoster

drivers/gpu/drm/imagination/pvr_vm.c

@@ -654,9 +654,7 @@ pvr_vm_context_lookup(struct pvr_file *pvr_file, u32 handle)
 
 	xa_lock(&pvr_file->vm_ctx_handles);
 	vm_ctx = xa_load(&pvr_file->vm_ctx_handles, handle);
-	if (vm_ctx)
-		kref_get(&vm_ctx->ref_count);
-
+	pvr_vm_context_get(vm_ctx);
 	xa_unlock(&pvr_file->vm_ctx_handles);
 
 	return vm_ctx;