staging: qlge: Deduplicate lbq_buf_size

staging: qlge: Deduplicate lbq_buf_size

lbq_buf_size is duplicated to every rx_ring structure whereas lbq_buf_order
is present once in the ql_adapter structure. All rings use the same buf
size, keep only one copy of it. Also factor out the calculation of
lbq_buf_size instead of having two copies.

Signed-off-by: Benjamin Poirier <bpoirier@suse.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20190927101210.23856-5-bpoirier@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>