Deep sleep stub may call ets_update_cpu_frequency, which has been moved from ROM to IRAM.
Restore the ROM version in the linker script, call it ets_update_cpu_frequency_rom, use it in the deep sleep stub.
This change allows setting pin configuration for EXT1 wakeup depending on the state of RTC_PERIPH power domain:
- if peripherals are enabled (due to another wakeup mode, or due to esp_deep_sleep_pd_config call), we can keep internal pullups/pulldowns enabled
- if peripherals are disabled, pullups and pulldowns need to be disabled as well
Also add comments about the purpose of registers being configured.
