Fix ECDSA signature verification

Fix ECDSA signature verification

[Patch #1] Fix signature verification.
[Patch #2] Fix compatibility.

Change-Id: Ib1b3769fc42143878d84f58830af1d3976409524
Signed-off-by: Dmitrii Zhuravlev <d.zhuravlev@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/3647
Reviewed-by: Hauke Mehrtens <hauke.mehrtens@lantiq.com>
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Sachin Agrawal <sachin.agrawal@intel.com>
(cherry picked from commit b5d9281374cd35e36e4bd348b4884d2f56d20ba8)
Reviewed-on: https://gerrit.iotivity.org/gerrit/3755