of: overlay: kmemleak in dup_and_fixup_symbol_prop()

mainline inclusion
from mainline-v5.7-rc2
commit 478ff649
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I77WRQ


CVE: NA

Reference: N/A

----------------------------------------------------------------

kmemleak reports several memory leaks from devicetree unittest.
This is the fix for problem 4 of 5.

target_path was not freed in the non-error path.

Fixes: e0a58f3e ("of: overlay: remove a dependency on device node full_name")
Reported-by: Erhard F. <erhard_f@mailbox.org>
Signed-off-by: Frank Rowand <frank.rowand@sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>