debugfs: make error message a bit more verbose

debugfs: make error message a bit more verbose

When a file/directory is already present in debugfs, and it is attempted
to be created again, be more specific about what file/directory is being
created and where it is trying to be created to give a bit more help to
developers to figure out the problem.

Cc: Stephen Rothwell <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Takashi Iwai <[email protected]>
Reviewed-by: Mark Brown <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>