wil6210: fix vendor command policy for vendor unspec commands

change the policy field in the vendor commands for
QCA_NL80211_VENDOR_SUBCMD_UNSPEC to be VENDOR_CMD_RAW_DATA.

This is a workaround for kernel 5.4 policy checks.
A complete solution for all vendor command policies will be submitted
later.

Change-Id: I889c86984a4835fed9bd96d487641fc5f4081faf
Signed-off-by: Ahmad Masri <amasri@codeaurora.org>