the FXM field needs to go through a one-hot "PriorityPicker" because using the fullmask is producing the wrong results.
change read_cr_whole to be a Data(8)
power_decode2.py use a PriorityPicker if bit 20 is 1 otherwise set equal to FXM straight.
this uses full_cr read enable as a madk, directly.
cr main_stage.py no longer expands FXM mask because full_cr only contains necessary fields.
write full cr mask likewise same thing.
no longer need to do read modify write because FXM (or onehot) is inherently the write enable, directly onto the full_cr.
commit 05bf9da9a9f4b9be556e28a8b0468009c639e1ae (HEAD -> master, origin/master)
Author: Luke Kenneth Casson Leighton <email@example.com>
Date: Sun Aug 30 15:45:03 2020 +0100
reversal of FXM mask for one-hot selection in OP_MTCR decode