wifi: iwlwifi: mld: fix HE SIG-B MCS/DCM/compression

wifi: iwlwifi: mld: fix HE SIG-B MCS/DCM/compression

These values should be taken from SIG-A, indicating how SIG-B
is encoded. The values taken from SIG-B (the corresponding
register) indicate how the data portion (for that user) is
encoded. For the SIG-B compression value the correct mask was
applied to the wrong value.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20251110150012.4d625e05dece.If295eb9382fc681d63b0853261d884cd1a833ba5@changeid