libnvdimm: fix badblock range handling of ARS range

libnvdimm: fix badblock range handling of ARS range

__add_badblock_range() does not account sector alignment when
it sets 'num_sectors'.  Therefore, an ARS error record range
spanning across two sectors is set to a single sector length,
which leaves the 2nd sector unprotected.

Change __add_badblock_range() to set 'num_sectors' properly.

Cc: <[email protected]>
Fixes: 0caeef63e6d2 ("libnvdimm: Add a poison list and export badblocks")
Signed-off-by: Toshi Kani <[email protected]>
Reviewed-by: Vishal Verma <[email protected]>
Signed-off-by: Dan Williams <[email protected]>