drm: Use size_t type for len variable in drm_copy_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 v4.14.296 by commit 5b5ba7d6c2efa416cbc6d2a4a4f2a301aa53af12. For more details please see the references link.