ALSA: ctxfi: 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/20201223172229.781-6-lars@metafoo.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/ctxfi/ctresource.c

@@ -209,7 +209,7 @@ int rsc_mgr_init(struct rsc_mgr *mgr, enum RSCTYP type,
 
 	mgr->type = NUM_RSCTYP;
 
-	mgr->rscs = kzalloc(((amount + 8 - 1) / 8), GFP_KERNEL);
+	mgr->rscs = kzalloc(DIV_ROUND_UP(amount, 8), GFP_KERNEL);
 	if (!mgr->rscs)
 		return -ENOMEM;