scsi/NCR5380: fix and standardize NDEBUG macros

All three NCR5380 core driver implementations share the same NCR5380.h
header file so they need to agree on certain macro definitions.

The flag bit used by the NDEBUG_MERGING macro in atari_NCR5380 and
sun3_NCR5380 collides with the bit used by NDEBUG_LISTS.

Moreover, NDEBUG_ABORT appears in NCR5380.c so it should be defined in
NCR5380.h rather than in each of the many drivers using that core.

An undefined NDEBUG_ABORT macro caused compiler errors and led to dodgy
workarounds in the core driver that can now be removed.
(See commits f566a576 and
185a7a1c.)

Move all of the NDEBUG_ABORT, NDEBUG_TAGS and NDEBUG_MERGING macro
definitions into NCR5380.h where all the other NDEBUG macros live.

Also, incorrect "#ifdef NDEBUG" becomes "#if NDEBUG" to fix the warning:
drivers/scsi/mac_scsi.c: At top level:
drivers/scsi/NCR5380.c:418: warning: 'NCR5380_print' defined but not used
drivers/scsi/NCR5380.c:459: warning: 'NCR5380_print_phase' defined but not used

The debugging code is now enabled when NDEBUG != 0.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Acked-by: Sam Creasey <sammy@sammy.net>
Signed-off-by: Christoph Hellwig <hch@lst.de>