defconfig: 8084: Increase default Kmemleak log size to 4000 from 400

The intention of this change is to help with memory leak
debugging, without any need to change the config file

Change-Id: I5a09ab3ff1d7352a8507962bfb55f86b93a6ca60
Signed-off-by: Monu Surana <msurana@codeaurora.org>