The opal_range_check_attributes_fd function expected both
offset and length parameters of a LR to be passed in sectors (512B).
During format we passed it wrongly in OPAL blocks which caused
bogus check provided OPAL block size was not 512B.
Fixes: #871.
Activating LUKS2 device with OPAL support is multistep process.
1) read LR state
2) unlock LR
3) activate dm device
4) in case step 3) failed lock the device
if in step 1) the device was locked.
Otherwise, in case parallel activation happened on one device
the process that failed to map dm device (device already active)
could relock the LR afterwards and effectively break already active
device.
To avoid that we do steps 1) through 4) protected by exclusive
opal lock unique per data block device configured for use with
LUKS2 OPAL support.
