soc/tegra: pmc: fix #ifdef block in header

soc/tegra: pmc: fix #ifdef block in header

When build testing on ARM without the PMC driver, the other drivers
fail to link:

ld.lld: error: undefined symbol: tegra_pmc_core_domain_state_synced
>>> referenced by regulators-tegra30.c
>>>               drivers/soc/tegra/regulators-tegra30.o:(tegra30_regulator_balance_voltage) in archive vmlinux.a
>>> referenced by regulators-tegra20.c
>>>               drivers/soc/tegra/regulators-tegra20.o:(tegra20_core_rtc_update) in archive vmlinux.a

Adapt the checks in the header to cover both cases on other architectures
and without PMC.

Fixes: 8318af5dd29c ("soc/tegra: pmc: Move legacy code behind CONFIG_ARM guard")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>