scsi: aic79xx: Use __ro_after_init explicitly

ahd_linux_setup_iocell_info() intentionally writes to the const-marked
aic79xx_iocell_info array, but is called during __init, so the location is
actually writable at this point on most architectures. Annotate this
explicitly with __ro_after_init to avoid static analysis confusion.

Link: https://lpc.events/event/16/contributions/1175/attachments/1109/2128/2022-LPC-analyzer-talk.pdf
Link: https://lore.kernel.org/r/20220914115953.3854029-1-keescook@chromium.org
Cc: Hannes Reinecke <hare@suse.com>
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org
Reported-by: David Malcolm <dmalcolm@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/aic7xxx/aic79xx_osm.c

@@ -194,7 +194,7 @@ struct ahd_linux_iocell_opts
 #define AIC79XX_PRECOMP_INDEX	0
 #define AIC79XX_SLEWRATE_INDEX	1
 #define AIC79XX_AMPLITUDE_INDEX	2
-static const struct ahd_linux_iocell_opts aic79xx_iocell_info[] =
+static struct ahd_linux_iocell_opts aic79xx_iocell_info[] __ro_after_init =
 {
 	AIC79XX_DEFAULT_IOOPTS,
 	AIC79XX_DEFAULT_IOOPTS,