dm verity: fix DM_VERITY_OPTS_MAX value yet again

Must account for the possibility that "try_verify_in_tasklet" is used.

This is the same issue that was fixed with commit 160f99db -- it
is far too easy to miss that additional a new argument(s) require
bumping DM_VERITY_OPTS_MAX accordingly.

Fixes: 5721d4e5 ("dm verity: Add optional "try_verify_in_tasklet" feature")
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

drivers/md/dm-verity-target.c

@@ -37,7 +37,7 @@
 #define DM_VERITY_OPT_AT_MOST_ONCE	"check_at_most_once"
 #define DM_VERITY_OPT_TASKLET_VERIFY	"try_verify_in_tasklet"
 
-#define DM_VERITY_OPTS_MAX		(3 + DM_VERITY_OPTS_FEC + \
+#define DM_VERITY_OPTS_MAX		(4 + DM_VERITY_OPTS_FEC + \
 					 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
 
 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;