intel/gen12: Take into account opcode when decoding SWSB

intel/gen12: Take into account opcode when decoding SWSB

The interpretation of the fields is different depending whether the
instruction is a SEND/MATH or not.

This fixes the disassembly output for non-SEND/MATH instructions that
have both in-order and out-of-order dependencies.  Their dependencies
were wrongly represented as `@A $B` when the correct would be `@A
$B.dst`.

Fixes: 6154cdf924f ("intel/eu/gen12: Add auxiliary type to represent SWSB information during codegen.")
Fixes: 83612c01271 ("intel/disasm/gen12: Disassemble software scoreboard information.")
Acked-by: Francisco Jerez <currojerez@riseup.net>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3660>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3660>