wcn36xx: Restore BEACON_TEMPLATE_SIZE

wcn36xx: Restore BEACON_TEMPLATE_SIZE

The BEACON_TEMPLATE_SIZE is used to describe the size of the beacon
template in SEND_BEACON_REQ as well as UPDATE_PROBE_RSP_TEMPLATE_REQ, in
the first case the beacon length is doubly encoded inside this buffer
while in the second its not.

Restore the BEACON_TEMPLATE_SIZE, to make UPDATE_PROBE_RSP_TEMPLATE_REQ
correct again and properly encode the double encoded length in the
SEND_BEACON_REQ case.

Also update the SEND_BEACON_REQ code path to mark the template size as
being the sum of the beacon size and the internal length marker.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>