drm: Use sizet type for len variable in drmcopy_field()
This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v6.0.3 by commit 81097f1a74c3cadaa25f5ef3002774a6cc895b4e. For more details please see the references link.