ARM: 7640/1: memory: tegra_ahb_enable_smmu() depends on TEGRA_IOMMU_SMMU

New SoC, Tegra114 also uses SMMU. Change tegra_ahb_enable_smmu()'s
dependency from ARCH_TEGRA_3x_SOC to TEGRA_IOMMU_SMMU. No need to edit
whenever a new Tegra SoC comes.

The following combination caused build error, which this patch fixes.

CONFIG_ARCH_TEGRA_2x_SOC=y
CONFIG_ARCH_TEGRA_114_SOC=y

drivers/iommu/tegra-smmu.c:485: undefined reference to gra_ahb_enable_smmu'

Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>