Fix Stack-buffer-over-flow while accessing remote device name

Issue:
During authentication timeout, if remote device name is invalid.
A two byte placeholder remote name is passed to callback to intimate
authentication failure. Callback is trying to access 248 bytes
of remote device name from the passed remote name which is of
two bytes. Mismatch of length between passed remote name and
accessed remote device name leads to buffer-over-flow

Fix:
Replaced remote device name to an array of 248 bytes from
two bytes array.

Test:Basic bluetooth pairing
Test:gd/cert/run
Bug: 161663998
Tag: #stability
Sponsor:cmanton@

Change-Id: I0f45a0cf4b1a12c874c2c1fe4dc165c76dc5ae90