[Bugfix][T106BUG-149][T106BUG-151]Fix apn_name, username, password, apn_type length error when using demo to add or set apn

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

Change-Id: Ifd732335c3c5fae62578910264a95f699fe4360c
1 file changed