drm/xe: Stop ignoring errors from xe_heci_gsc_init()

Do not ignore errors from xe_heci_gsc_init(). For example, it shouldn't
be fine to report successfully entering survivability mode when there's
no communication with gsc working. The driver should also not be
half-initialized in the normal case neither.

Cc: Riana Tauro <riana.tauro@intel.com>
Cc: Alexander Usyskin <alexander.usyskin@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250222001051.3012936-10-lucas.demarchi@intel.com


Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>