qed: replace bitmap_weight with bitmap_empty in qed_roce_stop()

qed_roce_stop() calls bitmap_weight() to check if any bit of a given
bitmap is set. We can do it more efficiently with bitmap_empty() because
bitmap_empty() stops traversing the bitmap as soon as it finds first set
bit, while bitmap_weight() counts all bits unconditionally.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Acked-by: Prabhakar Kushwaha <pkushwaha@marvell.com>