[SCSI] advansys: Move struct device out of the cfg structures

The cfg structures are supposed to be disposable after initialisation;
with the 'dev' used for DMA mapping in there, that's not possible.  Move
the dev to the board.

Also inline AscInitFromAscDvcVar into its only caller, remove some
unnecessary prototypes and sort out a few minor formatting issues.
Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>