libtcmu: fix hw_max_sectors max_xfer_len use
libtcmu: fix hw_max_sectors max_xfer_len use

Max sectors is the number of block_size sectors/blocks, so do not
convert between 512 bytes.

Signed-off-by: Mike Christie <39daeb1549a929782e38aa87c4e3da7f3844b09a@redhat.com>

open-iscsi/tcmu-runner,agrover/tcmu-runner,open-iscsi/tcmu-runner