drm/xe: Stop setting drvdata to NULL

drm/xe: Stop setting drvdata to NULL

PCI subsystem is not supposed to call the remove() function when probe
fails and doesn't need a protection for that. The only places checking
for NULL drvdata, is on 2 sysfs files and they shouldn't be needed since
the files are removed and reads on open fds just return an error.

For this protection the core driver implementation in
drivers/base/dd.c:device_unbind_cleanup() already sets it to NULL, after
the release of dev resources.

Remove the setting to NULL so it's possible to obtain the xe pointer
from callbacks like the component unbind from device_unbind_cleanup(),
i.e. after xe_pci_remove() already finished.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250222001051.3012936-5-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>