g_NCR5380: Kill compiler warning if builtin

If CONFIG_SCSI_GENERIC_NCR5380=y:

drivers/scsi/g_NCR5380.c:727: warning: 'id_table' defined but not used

In the non-modular case, MODULE_DEVICE_TABLE() expands to nothing, and
id_table is not referenced.

Correct the existing #ifdef to fix this.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>