[patch] mtd: use correct error codes in debugfs_create()

[Dan Carpenter]

On Fri, Jul 19, 2013 at 08:49:38AM +0300, Dan Carpenter wrote:
> The test here is reversed.  It should be that if "dent" is a valid error
> code then we use it, otherwise if it is NULL then use -ENODEV.
> 

People have explained the debugfs_create API to me better and now
I'm not sure what to do here...  debugfs_create_dir() returns a
NULL on error and if debugfs is not enabled then it returns -ENODEV.
We test for if (!IS_ENABLED(CONFIG_DEBUG_FS)) earlier in the
function so it can only return NULL.

Probably I should just change the test to only test for NULL?

Otherwise I think my patch is correct.  The original code will
return success on error (NULL return) and that was not intended.

regards,
dan carpenter