Match naming convention for other m_Specific* matchers, and frees up the
m_Opc() matcher for future use in #84940 to allow us to capture the
opcode of a unknown binop
Moving to m_SpecificOpc does mess up the formatting in a few places,
I've tried to refactor to use the m_Value(SDValue, ....) matcher where I
can to retrieve some whitespace
6832709dc0