strlcpy call size fixes, memory clearing

Usecase:
1. Run PTS test cases IIA BV-03-I/IIC BV-02-I/IID BV-01-I

Failure:
Randomly errors are returned for AT+BIA from PTS.

Cause:
Command parsing advances the check beyond the string end,
which is not guaranteed to be zeroed.

Fix:
Break string parsing when the end of string is encountered
after a AT+BIA argument.

Bug: 29615016

Change-Id: Ifc77435e780fba34006372694a7da4758e4f8c36