zlib_deflate/deftree: remove bi_reverse()

Remove bi_reverse() and use generic bitrev32() instead - it should have
better performance on some platforms.

Signed-off-by: yalin wang <yalin.wang2010@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>