Change in coreboot[master]: soc/intel/common/../cse: Create APIs for CSE device state transition

[Angel Pons (Code Review)]

Attention is currently required from: Furquan Shaikh, Maulik V Vaghela, Tim Wawrzynczak, Subrata Banik, Patrick Rudolph.
Angel Pons has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/57804 )

Change subject: soc/intel/common/../cse: Create APIs for CSE device state transition
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Patch Set 3:

(2 comments)

File src/soc/intel/common/block/cse/cse.c:

https://review.coreboot.org/c/coreboot/+/57804/comment/e4d1a141_c16f6e41 
PS3, Line 923: static bool is_cse_idle(void)
I just saw the follow-up patch. I'd make this function public (non-static), retype its return value to `enum cse_device_state` and rename it to something like `get_cse_device_state()`.

https://review.coreboot.org/c/coreboot/+/57804/comment/5b6016d2_aaa78fe1 
PS3, Line 946: set_cse_to_prior_state
> What's this `prior state`? Why not name this function `ensure_cse_idle`?

Ok, I just saw CB:57805 and the intended usage of this function. It should obtain the current state from `is_cse_idle()`, and take the prior state as a parameter.

Or one could make a single `bool set_cse_device_state(enum cse_device_state requested_state);` function that provides the functionality of `ensure_cse_active()` and `set_cse_to_prior_state()`. The function would check if the current state differs from the requested state, and put the CSE in the requested state if necessary, returning success/failure.

Together with `get_cse_device_state()`, the resulting API is flexible and straightforward to use.