exfat: sync'ed to latest driver from https://github.com/dorimanx/exfat-nofuse

thanks to @dorimanx and others who have contributed to exfat development

moved under fs/ to be the same as other fs drivers

Signed-off-by: Paul Reioux <reioux@gmail.com>

Conflicts:
	fs/exfat/README.md
	fs/exfat/exfat_api.c
	fs/exfat/exfat_api.h
	fs/exfat/exfat_bitmap.c
	fs/exfat/exfat_bitmap.h
	fs/exfat/exfat_blkdev.c
	fs/exfat/exfat_blkdev.h
	fs/exfat/exfat_cache.c
	fs/exfat/exfat_cache.h
	fs/exfat/exfat_config.h
	fs/exfat/exfat_core.c
	fs/exfat/exfat_core.h
	fs/exfat/exfat_data.c
	fs/exfat/exfat_data.h
	fs/exfat/exfat_nls.c
	fs/exfat/exfat_nls.h
	fs/exfat/exfat_oal.c
	fs/exfat/exfat_oal.h
	fs/exfat/exfat_super.c
	fs/exfat/exfat_upcase.c
	fs/exfat/exfat_version.h