arm: tegra12_defconfig: set 3GB-16MB task size

arm: tegra12_defconfig: set 3GB-16MB task size

The previously used 3GB-24MB task size caused relocation failures when
loading kernel modules. This happened because part of the module loading
area got beyond the 32MB relocation range from kernel .text segment.
This problem is ARM32-specific and does not affect ARM64.

Bug 1489463

Change-Id: I255eb605988b3095d49f05d4d4b199bf2c796bfd
Signed-off-by: Zheng Liu <zhliu@nvidia.com>
Reviewed-on: http://git-master/r/553996
Reviewed-by: Winnie Hsu <whsu@nvidia.com>
Tested-by: Winnie Hsu <whsu@nvidia.com>