[PATCH v5 2/3] lightnvm: add non-continuous lun target creation support

When create a target, we specify the begin lunid and the end lunid, and get the corresponding continuous luns from media manager, if one of the luns is not free, we failed to create the target, even if the device's total free luns are enough. So add non-continuous lun target creation support,

[PATCH v5 2/3] lightnvm: add non-continuous lun target creation support

When create a target, we specify the begin lunid and the end lunid, and get the corresponding continuous luns from media manager, if one of the luns is not free, we failed to create the target, even if the device's total free luns are enough. So add non-continuous lun target creation support,