Add pxp mode devstate to debugfs to monitor pxp state machine progress.
This is useful to debug issues in scenarios in which the pxp state
needs to be re-initialized, like during power transitions such as
suspend/resume. With this debugfs the state could be monitored
to ensure that pxp is in the ready state.

CC: Vitaly Lubart <vitaly.lubart@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220907215113.1596567-15-tomas.winkler@intel.comAcked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>