qed: rework qed_rdma_bmap_free()

qed_rdma_bmap_free() is mostly an opencoded version of printk("%*pb").
Using %*pb format simplifies the code, and helps to avoid inefficient
usage of bitmap_weight().

While here, reorganize logic to avoid calculating bmap weight if check
is false.

Signed-off-by: Yury Norov <yury.norov@gmail.com>