[DAG] ISD::VECTOR_INTERLEAVE and ISD::VECTOR_DEINTERLEAVE descriptions no longer match their behaviour

[RKSimon]

The doxygen descriptions in ISDOpcodes.h still assume the original (de)interleave2 behaviour, not the general interleave factors.

[topperc]

CC: @lukel97 @mshockwave

[RKSimon]

Sorry - too many Lukes :)

[lukel97]

Yeah I also noticed this earlier today, the new description should be something like:

  /// VECTOR_DEINTERLEAVE(VEC1, VEC2, ..., VECN) - Returns N vectors with all input and
  /// output vectors having the same type. The 0th output contains the 0 + i*N
  /// indices from CONCAT_VECTORS(VEC1, VEC2, ... VECN), the 1st output
  /// contains the 1 + i*N indices and so on. The relative order of elements within an
  /// output match that of the concatenated input.