R600/SI: Avoid generating S_MOVs with 64-bit immediates v2

SITargetLowering::analyzeImmediate() was converting the 64-bit values
to 32-bit and then checking if they were an inline immediate.  Some
of these conversions caused this check to succeed and produced
S_MOV instructions with 64-bit immediates, which are illegal.

v2:
  - Clean up logic

Reviewed-by: Christian König <christian.koenig@amd.com>
R600/SI: Add processor types for each SI variant

Reviewed-by: Christian König <christian.koenig@amd.com>
R600: Add RV670 processor

This is an R600 GPU with double support.

Reviewed-by: Christian König <christian.koenig@amd.com>
R600/SI: Use same names for corresponding MUBUF operands and encoding fields

The code emitter knows how to encode operands whose name matches one of
the encoding fields.  If there is no match, the code emitter relies on
the order of the operand and field definitions to determine how operands
should be encoding.  Matching by order makes it easy to accidentally break
the instruction encodings, so we prefer to match by name.

Reviewed-by: Christian König <christian.koenig@amd.com>
R600/SI: Add support for buffer stores v2

v2:
  - Use the ADDR64 bit

Reviewed-by: Christian König <christian.koenig@amd.com>