fw-api: CL 6431411 - update fw common interface files

fix HTT_PPDU_STATS_SEQ_TYPE start val; clean up HTT stats defs used w. pktlog
The HTT_PPDU_STATS_SEQ_TYPE enum values currently start with 0, which results in an inability to distinguish between the ppdu_seq_type not being specified (and thus defaulting to 0x0), versus being specified as HTT_SEQTYPE_SU, which currently has a value of 0.This change introduces a HTT_SEQTYPE_UNSPECIFIED = 0 enum value, and adds 1 to all current enum values.This change is not backwards compatible, but this is acceptable because neither host SW nor target FW have started using these new HTT_PDDU_STATS_SEQ_TYPE enums yet.This change also makes the following clean-ups within the HTT stats defs that are used within pktlog logging: Add htt_t2h_ppdu_stats_ind_hdr_t struct def (for use within FW, where endianness is known).Provide a struct def for the initial, non-HW dependent part of htt_ppdu_stats_sch_cmd_tlv_v.Change the array elements in htt_ppdu_stats_usr_common_array_tlv_v from A_UINT32 to htt_tx_ppdu_stats_info.Use union to show tag and length bitfields wtihin tag__length A_UINT32 field of htt_tlv_hdr_t.

Change-Id: If8c4dc098a870c01cbdd6d1aeef10fb3542f1ea2
CRs-Fixed: 2262693