dm zoned: use GFP_NOIO in I/O path

Use GFP_NOIO for memory allocations in the I/O path.  Other memory
allocations in the initialization path can use GFP_KERNEL.

Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>