mtd: parsers: ofpart: call of_node_put() only in ofpart_fail path

ofpart_none can only be reached after the for_each_child_of_node() loop
finishes. for_each_child_of_node() correctly calls of_node_put() for all
device nodes it iterates over as long as we don't break or jump out of
the loop.

Calling of_node_put() inside the ofpart_none path will wrongly decrement
the ref count of the last node in the for_each_child_of_node() loop.

Move the call to of_node_put() under the ofpart_fail label to fix this.

Fixes: ebd5a74db74e ("mtd: ofpart: Check availability of reg property instead of name property")
Signed-off-by: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@renesas.com>
Tested-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>