lightnvm: expose mccap in identify command

The mccap field is required for I/O command option support. It defines the
following flash access modes:

 * SLC mode
 * Erase/Program Suspension
 * Scramble On/Off
 * Encryption

It is slotted in between mpos and cpar, changing the offset for
cpar as well.

Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>