defconfig: msm8909: Don't restrict IOMMU mappings at 4K

Forcing 4K allocation and iommu mappings is a great
debugging strategy. But for performance reasons, disable
them.

Change-Id: I382023449229a7344b7ee43c888996bea93073ce
Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>
Signed-off-by: Susheel Khiani <skhiani@codeaurora.org>