i2c: tegra: only use new clock/reset APIs

Now that the standard clock/reset APIs are available for all Tegra SoCs,
convert the I2C driver to use them exclusively, and remove any references
to the custom Tegra-specific APIs.

Cc: Heiko Schocher <hs@denx.de>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>