ALSA: ctxfi: use enum type CT_SUM_CTL where appropriate

Currently a variable of type enum CT_AMIXER_CTL is used for enum
CT_SUM_CTL values. This leads to warnings when using clang:
sound/pci/ctxfi/ctmixer.c:945:32: warning: implicit conversion from enumeration type
      'enum CT_SUM_CTL' to different enumeration type 'enum CT_AMIXER_CTL'
      [-Wenum-conversion]
        for (i = AMIXER_MASTER_F, j = SUM_IN_F;
                                    ~ ^~~~~~~~
sound/pci/ctxfi/ctmixer.c:975:29: warning: implicit conversion from enumeration type
      'enum CT_SUM_CTL' to different enumeration type 'enum CT_AMIXER_CTL'
      [-Wenum-conversion]
        for (i = AMIXER_PCM_F, j = SUM_IN_F; i <= AMIXER_PCM_S; i++, j++) {
                                 ~ ^~~~~~~~

Introduce enum CT_SUM_CTL k and it instead.
Signed-off-by: NStefan Agner <stefan@agner.ch>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/pci/ctxfi/ctmixer.c

@@ -938,17 +938,18 @@ static int ct_mixer_topology_build(struct ct_mixer *mixer)
 	struct sum *sum;
 	struct amixer *amix_d, *amix_s;
 	enum CT_AMIXER_CTL i, j;
+	enum CT_SUM_CTL k;
 
 	/* Build topology from destination to source */
 
 	/* Set up Master mixer */
-	for (i = AMIXER_MASTER_F, j = SUM_IN_F;
-					i <= AMIXER_MASTER_S; i++, j++) {
+	for (i = AMIXER_MASTER_F, k = SUM_IN_F;
+					i <= AMIXER_MASTER_S; i++, k++) {
 		amix_d = mixer->amixers[i*CHN_NUM];
-		sum = mixer->sums[j*CHN_NUM];
+		sum = mixer->sums[k*CHN_NUM];
 		amix_d->ops->setup(amix_d, &sum->rsc, INIT_VOL, NULL);
 		amix_d = mixer->amixers[i*CHN_NUM+1];
-		sum = mixer->sums[j*CHN_NUM+1];
+		sum = mixer->sums[k*CHN_NUM+1];
 		amix_d->ops->setup(amix_d, &sum->rsc, INIT_VOL, NULL);
 	}
 
@@ -972,12 +973,12 @@ static int ct_mixer_topology_build(struct ct_mixer *mixer)
 	amix_d->ops->setup(amix_d, &amix_s->rsc, INIT_VOL, NULL);
 
 	/* Set up PCM-in mixer */
-	for (i = AMIXER_PCM_F, j = SUM_IN_F; i <= AMIXER_PCM_S; i++, j++) {
+	for (i = AMIXER_PCM_F, k = SUM_IN_F; i <= AMIXER_PCM_S; i++, k++) {
 		amix_d = mixer->amixers[i*CHN_NUM];
-		sum = mixer->sums[j*CHN_NUM];
+		sum = mixer->sums[k*CHN_NUM];
 		amix_d->ops->setup(amix_d, NULL, INIT_VOL, sum);
 		amix_d = mixer->amixers[i*CHN_NUM+1];
-		sum = mixer->sums[j*CHN_NUM+1];
+		sum = mixer->sums[k*CHN_NUM+1];
 		amix_d->ops->setup(amix_d, NULL, INIT_VOL, sum);
 	}