ofp-print: Avoid array overread in print_table_instruction_features().

ofp-print: Avoid array overread in print_table_instruction_features().

If a switch claimed to support an instruction that OVS does not know about,
then print_table_instruction_features() would read past the end of the
array of instruction names.  This fixes the problem.

None of the other uses of print_table_instruction_features() appear to have
the same problem.

Found by Coverity.

Reported-at: https://scan3.coverity.com/reports.htm#v16889/p10449/fileInstanceId=14762675&defectInstanceId=4305296&mergedDefectId=179859
Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Justin Pettit <jpettit@ovn.org>