Getting a error from blk->ops->write() is not a very unlikely
event (happens quite often during new board bringup), so we need to
catch and propagate them to upper layers so they can be at least
reported properly. Change the code of all of the callers to bail out
as soon as blk->ops->write() fails.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>