[Bugfix][T106BUG-208] fix ntp_sync_time return value wrong & optimize the use of "system()" function

Only Configure:No
Affected branch:master
Affected module:systime
Is it affected on both ZXIC and MTK: Yes
Self-test: Yes
Doc Update: No

Change-Id: Ic14500cee8643e5d3d18d55e677a6d939c126f7e
1 file changed