1. use spi functions in rom
2. remove unnecessary GPIO configurations.
3. remove unnecessary dummy settings.
4. enable dummy out function
5. flash and psram have independent timing setting registers.
6. no need to set 1.9v for LDO in 80Mhz
7. set IO driver ability to 1 by default.
8. no need to use GPIO matrix on esp32s2, IO MUX is recommended
9. enable spi clock mode and IO mode settings
1. Delete bootloader_clock_get_rated_freq_mhz, esp32s2 do not need it right now
2. Remove bootloader_flash_gpio_config () because it has the same function as bootloader_flash_dummy_config
