nvme: fix NVME_NS_DEAC may incorrectly identifying the disk as EXT_LBA.

The value of NVME_NS_DEAC is 3,
which means NVME_NS_METADATA_SUPPORTED | NVME_NS_EXT_LBAS. Provide a
unique value for this feature flag.

Fixes 1b96f862

 ("nvme: implement the DEAC bit for the Write Zeroes command")
Signed-off-by: Boyang Yu <yuboyang@dapustor.com>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>