i2c: tegra: Factor out hardware initialization into separate function

Factor out hardware initialization into a separate function from the probe
function. The only place where runtime PM needs to be resumed during probe
is the place of hardware initialization, hence it makes sense to factor
out it in order to have a bit cleaner error handling in tegra_i2c_probe().

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Tested-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>