ofproto-dpif-upcall: Use flow_wildcards_has_extra().

ofproto-dpif-upcall: Use flow_wildcards_has_extra().

Update the comment in ukey_revalidate() to reflect the fact that the
mask in ukey is not the datapath mask, but the originally translated
flow wildcards.

Use flow_wildcards_has_extra() instead of open coding equivalent (but
different) functionality.  The old form and the code in
flow_wildcards_has_extra() ((dp | wc != dp) and (dp & wc != wc),
respecively) give the same result:

dp   wc    (dp | wc != dp)        (dp & wc != wc)
-------------------------------------------------------
0    0      (0 | 0 != 0) (false)   (0 & 0 != 0) (false)
0    1      (0 | 1 != 0) (true)    (0 & 1 != 1) (true)
1    0      (1 | 0 != 1) (false)   (1 & 0 != 0) (false)
1    1      (1 | 1 != 1) (false)   (1 & 1 != 1) (false)

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>