defconfig: msm8916: Boost SMMU performance by dynamic mapping

Configs "IOMMU_FORCE_4K_MAPPING" and "ALLOC_BUFFERS_IN_4K_CHUNKS"
were meant for debugging purpose. With these, we partly simulated
fragmentation scenario for allocation and full unoptimized 2 level
SMMU mappings. Now for performance reason, disable them.

Change-Id: Ib91726b6ad0b57b238d0ff086da1ce90fb08b3f0
Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>