i2c: tegra: Enable new slave mode.

For Tegra i2c controller to function properly new slave mode must be
enabled.

swarren notes:

In particular, I found this was needed when working on enabling the
Tegra audio driver on the Seaboard board. There are two different PCB
layouts for this board; a "clamshell" version, which works just fine
without this change, and the original non-clamshell version, which needs
this change in order for I2C to operate correctly. Without it, I2C
probing fails for some devices, e.g. with:

wm8903 0-001a: Device with ID register 0 is not a WM8903
wm8903 0-001a: asoc: failed to probe CODEC wm8903.0-001a: -19
asoc: failed to instantiate card tegra-wm8903: -19
ALSA device list:
  No soundcards found.

Signed-off-by: Rakesh Iyer <riyer@nvidia.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>