Possibly redundant delay in Rtc::sleep

[dimpolo]

I'm unclear about the purpose of the 100ms delay before going to sleep here:

https://github.com/liebman/esp-hal/blob/2e2d67f315d7c3abf0d023fda541473858769965/esp-hal-common/src/rtc_cntl/mod.rs#L319C32-L319C32

@liebman suggested it might have been left in by mistake #574 (comment)

If so, we should remove the delay parameter of the various sleep methods

[bjoernQ]

We should probably double check with code in esp-idf - if they don't have that and everything works without we probably can/should remove it