x86/mce/dev-mcelog: use strscpy() to instead of strncpy()

The implementation of strscpy() is more robust and safer.
That's now the recommended way to copy NUL terminated strings.
Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
Signed-off-by: Yang Yang <yang.yang29@zte.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/202212031419324523731@zte.com.cn

arch/x86/kernel/cpu/mce/dev-mcelog.c

@@ -105,8 +105,7 @@ static ssize_t set_trigger(struct device *s, struct device_attribute *attr,
 {
 	char *p;
 
-	strncpy(mce_helper, buf, sizeof(mce_helper));
-	mce_helper[sizeof(mce_helper)-1] = 0;
+	strscpy(mce_helper, buf, sizeof(mce_helper));
 	p = strchr(mce_helper, '\n');
 
 	if (p)