mxser: fix xmit_buf leak in activate when LSR == 0xff
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 v4.9.311 by commit 376922045009f8ea2d20a8fa3475e95b47c41690, it was introduced in version v2.6.33 by commit 6769140d304731f0a3b177470a2adb4bacd9036b. For more details please see the references link.