[MTD] fix mtdconcat for subpage-write NAND
[MTD] fix mtdconcat for subpage-write NAND

This allows the mtdconcat driver to work with NAND flash devices that
support sub-page writes.

Signed-off-by: Chris Paulson-Ellis <711c73f64afdce07b7e38039a96d2224209e9a6c@edesix.com>
Signed-off-by: David Woodhouse <97b3379caa91f4ee97e44013ae4dc6350540fa9d@infradead.org>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas