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

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.

Signed-off-by: Martin George <marting@netapp.com>