Fix a bug in the block-erase optimization for Dataflash; it was using block
erase even for smaller segments that need page erase.

That wouldn't matter for JFFS2, which never erases less than one block
(sometimes several blocks), but for other callers it might.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: David Woodhouse <dwmw2@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>