softpipe: add missing sentinel to debug option array

softpipe: add missing sentinel to debug option array

Add DEBUG_NAMED_VALUE_END to finalize debug option array (see
lp_screen.c). Otherwise debug_get_flags_option might attempt to read
debug_named_value::name at an offset and SIGSEGV.

Signed-off-by: Heinrich Fink <hfink@snap.com>
Fixes: 991def0edc8 ("softpipe: Convert to comma-separated SOFTPIPE_DEBUG for debug options.")
Reviewed-by: Marcin Ślusarz <marcin.slusarz@intel.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11742>