defconfig: 8916: Re-enable forced 4K allocation/mapping

Forced 4K allocation and mapping for SMMU exploits the
SMMU for it's worst case. This helps in finding out
stability issues and performance impact in worst case.
Enable this until we want to switch to dynamic sized
allocation to get most perf benefits.

Change-Id: I7982b032ade225b22bcbf515da062066d694e9bd
Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>