dmaengine: idxd: fix memory leak in error handling path of idxd_alloc

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

dmaengine: idxd: fix memory leak in error handling path of idxd_alloc

Memory allocated for idxd is not freed if an error occurs during

idxd_alloc(). To fix it, free the allocated memory in the reverse order

of allocation before exiting the function in case of an error.