exfat: add bitmap operations

This adds the implementation of bitmap operations for exfat.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Sungjong Seo <sj1557.seo@samsung.com>
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Git-commit: 1e49a94cf707204b66a3fb242f2814712c941f52
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/


Change-Id: I6b3f723d89f772d70ff8468ef7bc5d944c25d21f
Signed-off-by: lixiang <lixiang@codeaurora.org>