fw-api: CL 24914490 - update fw common interface files

HTT stats: clean up stats struct names to facilitate automation
Apply the following cleanups and extensions in the htt_stats.h and htt.h files, to facilitate automatic generation of the .c code and .json layout specification files used by the ODD host+cloud framework to display HTT stats: Make the HTT TLV struct names be consistent with the TLV tag names (while keeping old names as aliases for the new names).Add specifications in htt_stats_tlv_tag_t enum elements to clarify how to publish the stats TLV object.Remove needless names in embedded structs, e.g. the _bar in struct bar { A_UINT32 a; struct _bar { A_UINT32 b; A_UINT32 c; } bar; };.Change no-element arrays to single-element arrays, e.g. change struct foo { struct bar_tlv bar[]; } to struct foo { struct bar_tlv bar[1]; }.
Change-Id: I671fba8a4d3fffcc77b6817a823e7b9000793754
CRs-Fixed: 2262693