No OPER-TLV are "empty TLVs".

No OPER-TLV are "empty TLVs".

As section 7 of RFC 5810 says, an OPER-TLV is 1*PATH-DATA-TLV, so it
always has at least one PATH-DATA-TLV.  Remove the ZERO_TTLV check - the
old one was bogus ((!ops->flags & ZERO_TTLV) means ((!ops->flags) &
ZERO_TTLV), and if ops->flags is non-zero, !ops->flags is zero, and the
test fails), and the new one causes tests to fail, revealing that the
whole "empty TLVs like COMMIT and TRCOMMIT are empty, we stop here"
think is wrong, so we remove it.