mtd: parsers: ofpart: fix OF node refcount leak in parse_fixed_partitions()

mtd: parsers: ofpart: fix OF node refcount leak in parse_fixed_partitions()

of_get_child_by_name() returns a node pointer with refcount incremented,
which must be released with of_node_put() when done. However, in
parse_fixed_partitions(), when dedicated is true (i.e., a "partitions"
subnode was found), the ofpart_node obtained from of_get_child_by_name()
is never released on any code path.

Add of_node_put(ofpart_node) calls on all exit paths when dedicated is
true to fix the reference count leak.

This bug was detected by our static analysis tool.

Fixes: 562b4e91d3b2 ("mtd: parsers: ofpart: fix parsing subpartitions")
Signed-off-by: Weigang He <geoffreyhe2@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>