For Dataflash, can_mark_obsolete = false and the NAND write buffering
code (wbuf.c) is used.

Since the DataFlash chip will automatically erase pages when writing,
the cleanmarkers are not needed - so cleanmarker_oob = false and
cleanmarker_size = 0

DataFlash page-sizes are not a power of two (they're multiples of 528
bytes).  The SECTOR_ADDR macro (added in the previous core patch) is
replaced with a (slower) div/mod version if CONFIG_JFFS2_FS_DATAFLASH is
selected.
Signed-off-by: NAndrew Victor <andrew@sanpeople.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!