ofproto-dpif: Actually log errors in facet_check_consistency()

facet_check_consistency() goes to some effort to create informative
error messages, protected by a rate limit, but does not actually
log these messages.

This appears to be an unintended side effect of
4dff90977694784e67e9c08cc72dee28ebc343ae ("ofproto-dpif: Move
odp_actions from subfacet to facet.").  This patch restores the
logging behaviour present prior to the above commit.

This patch also reverses a changes made by the same commit to use
ds_put_cstr() instead of ds_put_char() in facet_check_consistency().

Cc: Justin Pettit <jpettit@nicira.com>
Cc: Ethan Jackson <ethan@nicira.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Ethan Jackson <ethan@nicira.com>
dpif-netdev: Don't run port names through netdev_vport_get_dpif_port().

The ports that exist within a dpif have already been translated through
netdev_vport_get_dpif_port(), so there is no value to translating them
again in the interfaces that query or dump ports (and possibly a drawback
if somehow the translation could change).

After this change, dpif-netdev translates port names in just one place,
the port_add path, which makes dpif-netdev act the same way as dpif-linux
in this respect.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>
netdev-vport: Don't return static data in netdev_vport_get_dpif_port().

Returning a static data buffer makes code more brittle and definitely
not thread-safe, so this commit switches to using a caller-provided
buffer instead.

Signed-off-by: Ben Pfaff <blp@nicira.com>