intel/compiler: fix intel_swsb_decode for newer platforms

intel/compiler: fix intel_swsb_decode for newer platforms

In the previous patch we adjusted the scoreboard pass to take into
consideration a new case of unordered operations for TGL. Fix the
decoding as well.

v2: use intel_device_info_is_mtl()  (Curro, Jordan)
v3: the part where we export num_sources_from_inst() is now a separate patch
    (Curro).
v4: Work around false positive maybe-unitialized warning since Marge
    uses -Werror=maybe-uninitialized (Marge).

Reviewed-by: Francisco Jerez <currojerez@riseup.net> (v3)
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20072>