fw-api: CL 7134963 - update fw common interface files

HTT stats: partly remove target_type field from htt_ppdu_stats_sch_cmd TLV
The target_type field is not actually present in the HTT messages produced by the FW. However, it cannot be fully removed (yet), due to FW code that refers to this field.As a workaround, this target_type field is being moved into a union with the hw field that actually is present in the message.This makes the message definitions become consistent with the actual message contents, while not breaking the compilation of code that refers to the target_type field.Overlaying the memory for target_type and hw does not cause problems, because the FW code that refers to target_type first writes a value into the target_type field, then writes data into the hw field.Once all FW references to the target_type field have been removed, the target_type field def and the encapsulating anonymous union will be removed from the htt_ppdu_stats_sch_cmd_tlv_v struct def.

Change-Id: Ibd789e350e392591b12edb0478c224c737b0fe3e
CRs-Fixed: 2262693