atp870u: Initialize tables earlier

Call _init_tables before chip-specific initialization. This avoids code
duplication and fixes a bug(?) in 880 init where the values read from flash
into atpdev->sp are then overwritten by calling init_tables.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Reviewed-by: Hannes Reinicke <hare@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>