UBI: block: Remove __initdata from ubiblock_param_ops

You cannot mark these parameters as __initdata.
Otherwise the data is gone upon module exit.

Fixes:
[  172.045465] BUG: unable to handle kernel paging request at ffffffffa001db38
[  172.046020] IP: [<ffffffff81067aa4>] destroy_params+0x24/0x50

Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>