multipath: Set 'tur' as the default path checker for NetApp LUNs

In our tests, we've noticed that the 'tur' checker provides better performance compared to 'directio' primarily because 'tur' does not use FS-based requests unlike 'directio'. Moreover with Hannes' recent async tur enhancement, the 'tur' checker is more efficient now than before.

So we'd prefer using 'tur' as the default path checker for NetApp LUNs now. The below patch enables the same by updating the .checker_name in the hwtable for NetApp LUNs.

---
 libmultipath/hwtable.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

index 020c8aa..b8a62dd 100644
@@ -955,7 +955,7 @@ static struct hwentry default_hw[] = {
 		.rr_weight     = RR_WEIGHT_NONE,
 		.no_path_retry = NO_PATH_RETRY_UNDEF,
 		.minio         = 128,
-		.checker_name  = DIRECTIO,
+		.checker_name  = TUR,
 		.prio_name     = PRIO_ONTAP,
 		.prio_args     = NULL,
 	},

1.6.3.3