ARM: NCP: make ncp_iodesc static and move it to initdata section

Make ncp_iodesc struct static to clean a public namespace a bit and move
it to __initdata section to save memory a bit.

Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>