The gpudev functions free, register and unregister
return gracefully if input pointer is NULL or size 0,
as API doc was indicating no-op accepted values.
CUDA driver checks are removed because redundant
with the checks added in gpudev library.
Fixes: e818c4e2bf50 ("gpudev: add memory API")
Signed-off-by: Elena Agostini <eagostini@nvidia.com>
1674c56dc3