drm/xe/pf: Allow to save and restore VF config blob from debugfs

For feature enabling and testing purposes, allow to capture and
replace full VF configuration using debugfs blob file, but only
under strict debug config.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240919171528.1451-6-michal.wajdeczko@intel.com