ANDROID: suppress GKI configs for 32-bit builds

For kernelci 32-bit allmodconfig builds, we get warnings like:

WARNING: unmet direct dependencies detected for IOMMU_IO_PGTABLE_LPAE
  Depends on [n]: IOMMU_SUPPORT [=y] && (ARM [=y] || ARM64 || COMPILE_TEST [=y]) && !GENERIC_ATOMIC64 [=y]
  Selected by [y]:
  - GKI_HIDDEN_QCOM_CONFIGS [=y] && ARCH_QCOM [=y]

Since GKI is only for 64-bit builds, ignore init/Kconfig.gki if !64BIT

Bug: 379954362
Signed-off-by: Todd Kjos <tkjos@google.com>
Change-Id: Ibe1880a6d30020e4fe63354273e74c0aece3d327