drm: amdgpu: Allow NULL pointers at amdgpu_vm_put_task_info()

Allow NULL pointers at amdgpu_vm_put_task_info() as it common practice
for "put" or "free" functions. This avoid an extra check for NULL for
callers.

Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20250617124949.2151549-2-andrealmeid@igalia.com


Signed-off-by: André Almeida <andrealmeid@igalia.com>