clk: tegra: fix ifdef for tegra_periph_reset_assert inline

Commit 7064f6bd "clk: tegra: provide tegra_periph_reset_assert
alternative" added ifdef'd static inline versions of some functions,
but tested ARCH_TEGRA rather than CONFIG_ARCH_TEGRA, thus disabling
these function in all cases. In some cases, this caused HW modules to
misbehave; for example, the Tegra I2C driver BUG()d during boot on
Seaboard.

Reported-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Paul Walmsley <pwalmsley@nvidia.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>