Pull another MTD fix from Brian Norris:
"An mtdblock regression occurred in -rc1 (all writes were broken!), in
the process of some block subsystem refactoring. Noticed and fixed
last week, but I'm a little slow on the uptake"
* tag 'for-linus-20170812' of git://git.infradead.org/linux-mtd:
mtd: blkdevs: Fix mtd block write failure