cpu/esp32: set bootloader XTAL frequency configuration to automatic #18829
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Contribution description
Sets the XTAL frequency configuration of the ESP32 bootloader to automatic (0). Before that, it was fixed/hardcoded to 40 MHz which results in UART output problems with non-40MHz boards such as the one in #18828.
Testing procedure
If you've a board with 26 MHz XTAL crystal at hand, flash and test any shell based application:
make BOARD=esp32-wroom-32 -C tests/shell
. If not, all tests should still pass on all ESP32 boards.If everything works, UART will output text normally. Before the PR, rubbish should appear such as in the actual results of #18828.
Issues/PRs references
Fixes #18828.
Follow-up to #13059.