ARM: tegra: use correct audio CODEC on Jetson TK1

Jetson TK1 contains an RT5639 not an RT5640. While the two are extremely
similar and mostly compatible, we should still use the correct device
name in the device tree. I had meant to fix this before applying the
initial DT, but this issue slipped my mind.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>