ANDROID: GKI: arm64: gki_defconfig: Set arm_smmu configuration

Set CONFIG_ARM_SMMU=m to allow vendor implementations.
Set CONFIG_IOMMU_IO_PGTABLE_FAST=y since it's used by vendors.

Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Test: compile
Bug: 155522481
Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Change-Id: I257897275fbfe34ca74534551050b73010068115
Signed-off-by: Saravana Kannan <saravanak@google.com>