of: Fix issue where code would fall through to error case.

No longer fall through into the error case that prints out
an error if no error (err = 0) occurred.

Fixes d9181b20(of: Add back an error message, restructured)
Signed-off-by: Moritz Fischer <mdf@kernel.org>
Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>