ofproto: Use proper error code when meter_id is out of range.

Use OUT_OF_METERS when given meter_id is greater than what is supported
by the datapath.  Retain the INVALID_METER error code for the meter_ids
outside of the range supported by the specification.

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