Add exFAT 1.2.4 driver from Samsung

Available from http://opensource.samsung.com/
Merge branch 'samsung'

Keep some fixes from the rxrz initial release.
Merge remote-tracking branch 'origin/master' into merged

Conflicts:
	Makefile
	exfat_api.c
	exfat_config.h
	exfat_core.c
	exfat_super.c
	exfat_super.h
	exfat_version.h