cnss2: NULL terminate FW build ID string

If FW build ID passed by QMI from firmware is a non-NULL terminated
string, it will result in a out-of-bounds read when driver populates
the QMI message using strlcpy where the src string must be NULL
terminated. Hence manually NULL terminate the string.

Change-Id: I8e27c01eae79e56afd1a706d071b4ccfa51d79e0
Signed-off-by: Yue Ma <yuem@codeaurora.org>