zd1211rw: document need for kmalloc cast

Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/wireless/zd1211rw/zd_chip.c

@@ -117,6 +117,7 @@ int zd_ioread32v_locked(struct zd_chip *chip, u32 *values, const zd_addr_t *addr
 
 	/* Allocate a single memory block for values and addresses. */
 	count16 = 2*count;
+	/* zd_addr_t is __nocast, so the kmalloc needs an explicit cast */
 	a16 = (zd_addr_t *) kmalloc(count16 * (sizeof(zd_addr_t) + sizeof(u16)),
 		                   GFP_KERNEL);
 	if (!a16) {