drm/etnaviv: Replace strncpy with strscpy_pad

`strncpy` is deprecated for use on NUL-terminated destination strings [1].

We should prefer more robust and less ambiguous string interfaces.

A suitable replacement is `strscpy_pad` due to the fact that it
guarantees NUL-termination on the destination buffer whilst maintaining
the NUL-padding behavior that strncpy provides.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: KSPP#90
Cc: linux-hardening@vger.kernel.org
Cc: Bo YU <tsu.yubo@gmail.com>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Christian Gmeiner <cgmeiner@igalia.com>
[lst: changed subject according to suggestion from Kees]
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

Author: JustinStitt

drivers/gpu/drm/etnaviv/etnaviv_perfmon.c

@@ -511,7 +511,7 @@ int etnaviv_pm_query_dom(struct etnaviv_gpu *gpu,
 
 	domain->id = domain->iter;
 	domain->nr_signals = dom->nr_signals;
-	strncpy(domain->name, dom->name, sizeof(domain->name));
+	strscpy_pad(domain->name, dom->name, sizeof(domain->name));
 
 	domain->iter++;
 	if (domain->iter == nr_domains)
@@ -540,7 +540,7 @@ int etnaviv_pm_query_sig(struct etnaviv_gpu *gpu,
 	sig = &dom->signal[signal->iter];
 
 	signal->id = signal->iter;
-	strncpy(signal->name, sig->name, sizeof(signal->name));
+	strscpy_pad(signal->name, sig->name, sizeof(signal->name));
 
 	signal->iter++;
 	if (signal->iter == dom->nr_signals)