kselftest: alsa: fixed a print formatting warning

A statement used %d print formatter where %s should have
been used. The same has been fixed in this commit.

Signed-off-by: Ghanshyam Agrawal <ghanshyam1898@gmail.com>
Link: 5aaf9ef ("kselftest: alsa: Add simplistic test for ALSA mixer controls kselftest")
Link: https://lore.kernel.org/r/20231217080019.1063476-1-ghanshyam1898@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Author: ghanshyam1898

tools/testing/selftests/alsa/mixer-test.c

@@ -138,7 +138,7 @@ static void find_controls(void)
 			err = snd_ctl_elem_info(card_data->handle,
 						ctl_data->info);
 			if (err < 0) {
-				ksft_print_msg("%s getting info for %d\n",
+				ksft_print_msg("%s getting info for %s\n",
 					       snd_strerror(err),
 					       ctl_data->name);
 			}