drivers: i3c: common: add reference to address restrictions

This makes actions taken by the code easier to follow for newbies like
me.

Signed-off-by: Gerard Marull-Paretas <[email protected]>

drivers/i3c/i3c_common.c

@@ -97,6 +97,7 @@ int i3c_addr_slots_init(const struct device *dev)
 	sys_slist_init(&data->attached_dev.devices.i3c);
 	sys_slist_init(&data->attached_dev.devices.i2c);
 
+	/* Address restrictions (ref 5.1.2.2.5, Specification for I3C v1.1.1) */
 	for (i = 0; i <= 7; i++) {
 		/* Addresses 0 to 7 are reserved */
 		i3c_addr_slots_set(&data->attached_dev.addr_slots, i, I3C_ADDR_SLOT_STATUS_RSVD);