dcb : Fix incorrect documentation for struct dcb_app

While IEEE and CEE use the same structure to store apps, the selector
and priority fields for both are different. Only the priority field is
explained, add documentation explaining how the selector field differs
for both.

cgdcbxd code shows an example of how selector fields differ.

Signed-off-by: Anish Bhatt <anish@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/dcbnl.h

@@ -207,22 +207,26 @@ struct cee_pfc {
 #define IEEE_8021QAZ_APP_SEL_ANY	4
 
 /* This structure contains the IEEE 802.1Qaz APP managed object. This
- * object is also used for the CEE std as well. There is no difference
- * between the objects.
+ * object is also used for the CEE std as well.
  *
  * @selector: protocol identifier type
  * @protocol: protocol of type indicated
  * @priority: 3-bit unsigned integer indicating priority for IEEE
  *            8-bit 802.1p user priority bitmap for CEE
  *
  * ----
- *  Selector field values
+ *  Selector field values for IEEE 802.1Qaz
  *	0	Reserved
  *	1	Ethertype
  *	2	Well known port number over TCP or SCTP
  *	3	Well known port number over UDP or DCCP
  *	4	Well known port number over TCP, SCTP, UDP, or DCCP
  *	5-7	Reserved
+ *
+ *  Selector field values for CEE
+ *	0	Ethertype
+ *	1	Well known port number over TCP or UDP
+ *	2-3	Reserved
  */
 struct dcb_app {
 	__u8	selector;