[patch] mtd: silence some uninitialized variable warnings

[Brian Norris]

On Wed, Apr 13, 2016 at 09:42:34AM +0300, Dan Carpenter wrote:
> The "tmp_retlen" variable can be uninitialized if action() fails.  It's
> harmless except for the static checker warning.  I have moved the error
> handling earlier to fix it.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>

Applied to l2-mtd.git