hw/nvme: fix lbaf formats initialization

Currently LBAF formats are being intialized based on metadata
size if and only if nvme-ns "ms" parameter is non-zero value.
Since FormatNVM command being supported device parameter "ms"
may not be the criteria to initialize the supported LBAFs.

And make LBAF array as read-only.

Signed-off-by: Gollu Appalanaidu <anaidu.gollu@samsung.com>
Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>