sparse: eliminate "duplicate initialization" warning

Sparse version 0.5.1 will be released in the near future. Prepare
for it by eliminating the only new warning (as of 0.5.1-rc5):

ofproto/fail-open.c:134:22: error: Initializer entry defined twice
ofproto/fail-open.c:135:22:   also defined here

MATCH_CATCHALL_INITIALIZER effectively sets all fields of .flow to
zero, which is redundant because according to the C99 semantics for
structure initialization, initializing any single member of a
structure results in all other members being initialized to zero,
and the next line initializes a member of the same structure.

Signed-off-by: Lance Richardson <lrichard@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>
Reviewed-by: Greg Rose <gvrose8192@gmail.com>

ofproto/fail-open.c

@@ -131,7 +131,6 @@ send_bogus_packet_ins(struct fail_open *fo)
                 .base = {
                     .packet = dp_packet_data(&b),
                     .packet_len = dp_packet_size(&b),
-                    .flow_metadata = MATCH_CATCHALL_INITIALIZER,
                     .flow_metadata.flow.in_port.ofp_port = OFPP_LOCAL,
                     .flow_metadata.wc.masks.in_port.ofp_port
                     = u16_to_ofp(UINT16_MAX),