Despite its name, MI_FLUSH_DW instruction can write an immediate value
of either dword size or qword size, depending on the 'length' field of
the instruction.  Since "length" excludes the first two dwords of the
instruction, a value of 2 in the length field implies a dword write and
a value of 3 implies a qword write.  Even in cases where the flush
instruction's post-sync operation is set to "no write" we're still
expected to size the overall instruction as if we were doing a dword or
qword write (i.e., a length of 1 shouldn't be used on modern platforms).

Rather than baking a size of "1" into the #define and then adding
another unexplained "+ 1" at all the spots where the definition gets
used, lets just create MI_FLUSH_IMM_DW and MI_FLUSH_IMM_QW definitions
that should be OR'd into the instruction header to make it more explicit
what behavior we're requesting.

Bspec: 60229
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20231016163449.1300701-9-matthew.d.roper@intel.comSigned-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>