ncr5380: Remove useless prototypes

Add missing static qualifiers and remove the now pointless prototypes. The
NCR5380_* prototypes are all declared in NCR5380.h and renamed using macros.
Further declarations are redundant (some are completely unused). Remove
them.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>