[MTD] DataFlash: fix bug - ATMEL AT45DF321D spi flash card fails to be copied to (v2)

 - Add support for binary page size DataFlashes.
 - The driver now prints out pagesize and erasesize.
   Printout valuable information for creating flash filesystems.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>