RDMA/mlx5: Fix memory leak in GET_DATA_DIRECT_SYSFS_PATH handler

In the Linux kernel, the following vulnerability has been resolved:

RDMA/mlx5: Fix memory leak in GET_DATA_DIRECT_SYSFS_PATH handler

The UVERBS_HANDLER(MLX5_IB_METHOD_GET_DATA_DIRECT_SYSFS_PATH) function

allocates memory for the device path using kobject_get_path(). If the

length of the device path exceeds the output buffer length, the function

returns -ENOSPC but does not free the allocated memory, resulting in a

memory leak.

Add a kfree() call to the error path to ensure the allocated memory is

properly freed.

Compile tested only. Issue found using a prototype static analysis tool

and code review.