ath10k: Fix the parsing error in service available event

The wmi service available event has been
extended to contain extra 128 bit for new services
to be indicated by firmware.

Currently the presence of any optional TLVs in
the wmi service available event leads to a parsing
error with the below error message:
ath10k_snoc 18800000.wifi: failed to parse svc_avail tlv: -71

The wmi service available event parsing should
not return error for the newly added optional TLV.
Fix this parsing for service available event message.

Tested-on: WCN3990 hw1.0 SNOC WLAN.HL.3.2.2-00720-QCAHLSWMTPL-1

Fixes: cea19a6c

 ("ath10k: add WMI_SERVICE_AVAILABLE_EVENT support")
Signed-off-by: Rakesh Pillai <pillair@codeaurora.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1605501291-23040-1-git-send-email-pillair@codeaurora.org