mei: debugfs: add pxp mode to devstate in debugfs

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.com


Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>