ARM: enable SUSPEND/ARCH_SUSPEND_POSSIBLE for ARCH_TEGRA

Even though system suspend/resume hasn't been validated on Tegra yet,
this Kconfig option needs to be enabled so that system shutdown is
reliable on an SMP system. Without it, I2C interrupts may be routed
to CPU0, whereas shutdown code may be running on CPU1, causing I2C
timeouts, preventing communication with the external PMIC.

This reverts 3d5e8af4 "ARM: disable SUSPEND/ARCH_SUSPEND_POSSIBLE for
ARCH_TEGRA".

Signed-off-by: Stephen Warren <swarren@nvidia.com>