soc/tegra: pmc: Drop SMP dependency from CPU APIs

When CONFIG_SMP is disabled, the tegra clk driver now fails to build:

drivers/clk/tegra/clk-tegra30.c: In function ‘tegra30_cpu_rail_off_ready’:
drivers/clk/tegra/clk-tegra30.c:1151:2: error: implicit declaration of function ‘tegra_pmc_cpu_is_powered’ [-Werror=implicit-function-declaration]
  cpu_pwr_status = tegra_pmc_cpu_is_powered(1) ||
    ^
Fix the above error by removing the CONFIG_SMP ifdef around the
declaration around the PMC CPU APIs because although these are not
needed for non-SMP configurations, there is no harm in including these
for non-SMP builds either.

Fixes: 61866523ed6e ("clk: tegra30: Use Tegra CPU powergate helper function")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>