Autodetect xtal-freq

[SergioGasquez]

• Removed xtal-26mhz and xtal-40mhz features
• Use RtcClock::estimate_xtal_frequency() to select the crystal frequency as suggested in Can we auto detect xtal reliably at runtime? #1164
  • Chose 33 to be the limit of the two freqs as that is what esptool uses (in different scenario, but I think it makes sense to reuse it)

Draft until properly tested:

• Tried testing it using a simple apps and debugging it with probe-rs but encountered Disabled breakpoints probe-rs/probe-rs#2180.
• I've also tried creating esp-flasher-stubs using esp-hal with this changes and I was able to flash 26 and 40 Mhz C2s but espflash will report 40MHz as xtal freq in both cases (Its guessed using UART_CLKDIV_REG, which is the same for both xtal freqs not sure why).

Tests:

• I've tested enabling esp-hal logs and printing the value of RtcClock::estimate_xtal_frequency() in https://github.com/esp-rs/esp-hal/pull/1165/files#diff-75a5e847ec368b58a227b16ea788a0007a569040ed5793bf8cdda6f37676f0f5R384 and usually is 25 for 26MHz and 38 for 40MHz

[SergioGasquez]

I think the current PR already solves #1164, but it does not resolve the TODO of implementing estimate_xtal_frequency for C6 and H2. Only ESP32 and ESP32-C2 use estimate_xtal_frequency to select the xtal-freqs, the rest of the chips are hardcoded freqs.

We could also implement the estimate_xtal_frequency for the missing targets and use it to resolve #1127 as @jessebraham suggested.

[jessebraham]

Probably fine to implement those in a separate PR rather than hold things up here, but your call obviously. I think removing the crystal frequency features is a huge win already!

[jessebraham]

Sorry I updated the CI workflow without thinking, so this will need a quick rebase

[MabezDev]

Nice!!! Thanks for looking into this, I'm stoked to remove some features :D.

I have a few comments, but nothing major. I don't actually have any 26/24mhz esp's so I can't test it myself, sorry.

[bjoernQ]

Besides the other comments LGTM - tested with ESP32-C2 26MHz

[JurajSadel]

LGTM!

[MabezDev]

Thanks for working on this! LGTM!