staging: lustre: libcfs: Fix libcfs_ioctl() prototype.

Fix libcfs_ioctl() prototype according to its definition in
libcfs/module.c.

Signed-off-by: Aleksei Fedotov <lexa@cfotr.com>
Acked-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>