os/bluestore: use p2 macros to simplify bit-allocator block alignment

os/bluestore: use p2 macros to simplify bit-allocator block alignment

Mark's comments:

This passed "ceph_test_objectstore --gtest_filter=*/2".
This PR did not appear to have a significant impact on performance tests.

Closes #10253

os/bluestore: require block_size to be power of 2 aligned

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>
os/bluestore: use ISP2 macro for zone/span size checking

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>