HID: prodikeys: Replace deprecated strncpy() with strscpy()

`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` [2] due to the fact that it guarantees
NUL-termination on the destination buffer without unnecessarily NUL-padding.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: KSPP#90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230914-strncpy-drivers-hid-hid-prodikeys-c-v1-1-10c00550f2c2@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>

Author: JustinStitt

drivers/hid/hid-prodikeys.c

@@ -639,9 +639,9 @@ static int pcmidi_snd_initialise(struct pcmidi_snd *pm)
 		goto fail;
 	}
 
-	strncpy(card->driver, shortname, sizeof(card->driver));
-	strncpy(card->shortname, shortname, sizeof(card->shortname));
-	strncpy(card->longname, longname, sizeof(card->longname));
+	strscpy(card->driver, shortname, sizeof(card->driver));
+	strscpy(card->shortname, shortname, sizeof(card->shortname));
+	strscpy(card->longname, longname, sizeof(card->longname));
 
 	/* Set up rawmidi */
 	err = snd_rawmidi_new(card, card->shortname, 0,
@@ -652,7 +652,7 @@ static int pcmidi_snd_initialise(struct pcmidi_snd *pm)
 		goto fail;
 	}
 	pm->rwmidi = rwmidi;
-	strncpy(rwmidi->name, card->shortname, sizeof(rwmidi->name));
+	strscpy(rwmidi->name, card->shortname, sizeof(rwmidi->name));
 	rwmidi->info_flags = SNDRV_RAWMIDI_INFO_INPUT;
 	rwmidi->private_data = pm;