ath10k: refactor phyerr event handlers

Existing phyerr event handlers directly uses phyerr header format
(ie, struct wmi_phyerr and struct wmi_phyerr_event) in the code
exactly on how firmware packs it. This is the problem in 10.4 fw
specific phyerr event handling where it uses different phyerror
header format. Before adding 10.4 specific handler, little bit of
refactor is done in existing phyerr handlers.

Two new abstracted structures (struct wmi_phyerr_ev_hdr_arg and
struct wmi_phyerr_ev_arg) are introduced to remove dependency of using
firmware specific header format in the code. So that firmware specific
phyerror handlers can populate values to abstracted structures and
the following code can use abstracted struct for further operation.

.pull_phyerr_hdr is added newly to pull common phyerr header info
like tsf, buf_len, number of phyerr packed. Existing .pull_phyerr
handler is changed and called to parse every sub phyerrs in the event.

Validated these refactoring on qca988x hw2.0 using fw 10.2.4 version.

Signed-off-by: Raja Mani <rmani@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>