ALSA: usb: Use DIV_ROUND_UP() instead of open-coding it

Use DIV_ROUND_UP() instead of open-coding it. This documents intent
and makes it more clear what is going on for the casual reviewer.

Generated using the following the Coccinelle semantic patch.

// <smpl>
@@
expression x, y;
@@
-(((x) + (y) - 1) / (y))
+DIV_ROUND_UP(x, y)
// </smpl>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Link: https://lore.kernel.org/r/20201223172229.781-11-lars@metafoo.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/mixer.c

@@ -254,7 +254,7 @@ static int get_relative_value(struct usb_mixer_elem_info *cval, int val)
 	if (val < cval->min)
 		return 0;
 	else if (val >= cval->max)
-		return (cval->max - cval->min + cval->res - 1) / cval->res;
+		return DIV_ROUND_UP(cval->max - cval->min, cval->res);
 	else
 		return (val - cval->min) / cval->res;
 }
@@ -1338,7 +1338,7 @@ static int mixer_ctl_feature_info(struct snd_kcontrol *kcontrol,
 		}
 		uinfo->value.integer.min = 0;
 		uinfo->value.integer.max =
-			(cval->max - cval->min + cval->res - 1) / cval->res;
+			DIV_ROUND_UP(cval->max - cval->min, cval->res);
 	}
 	return 0;
 }