scsi: ncr5380: Avoid a compiler warning

With commit 3a0f64bf ("mac_scsi: Fix pseudo DMA implementation")
some versions of gcc now warn:

In file included from drivers/scsi/mac_scsi.c:335:
drivers/scsi/NCR5380.h:295: warning: `NCR5380_poll_politely' declared inline after being called
drivers/scsi/NCR5380.h:295: warning: previous declaration of `NCR5380_poll_politely' was here

Avoid this by defining NCR5380_poll_politely() in NCR5380.h.

[mkp: checkpatch warnings]

Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>