memory corruption on bluetooth stack.

This memory corruption will happen if the remote BLE device name
is more than 249 bytes (the maximum attribute length our BLE support is 600.).
after we send/receive GATT remote device name service attribute.
 We will copy upto 600 bytes data to a local name buffer with size of 249.
This will cause serious memory corruption on the stack memory.

bug:12570982
Change-Id: I5b2ffd5f5a16f4d80d5491e86bf18bf47e30629e