switchdev: documentation: use switchdev_port_obj_xxx for IPv4 FIB add/modify/delete ops

Clarify in documentation and code that IPV4 FIB add operation is used for
both adding a new FIB entry to the device and for modifying an existing FIB
entry on the device.

Also, remove left-over references to ipv4_fib ops and replace with details
on SWITCHDEV_PORT_IPV4_FIB object.

Signed-off-by: Scott Feldman <sfeldma@gmail.com>
Acked-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/switchdev/switchdev.c b/net/switchdev/switchdev.c
index ac853ac..e008057 100644
--- a/net/switchdev/switchdev.c
+++ b/net/switchdev/switchdev.c
@@ -803,7 +803,7 @@
 }
 
 /**
- *	switchdev_fib_ipv4_add - Add IPv4 route entry to switch
+ *	switchdev_fib_ipv4_add - Add/modify switch IPv4 route entry
  *
  *	@dst: route's IPv4 destination address
  *	@dst_len: destination address length (prefix length)
@@ -813,7 +813,7 @@
  *	@nlflags: netlink flags passed in (NLM_F_*)
  *	@tb_id: route table ID
  *
- *	Add IPv4 route entry to switch device.
+ *	Add/modify switch IPv4 route entry.
  */
 int switchdev_fib_ipv4_add(u32 dst, int dst_len, struct fib_info *fi,
 			   u8 tos, u8 type, u32 nlflags, u32 tb_id)