wcn36xx: pass information elements in scan requests

When the wifi driver core passes IE elements in the scan request, append
them to the firmware message. The driver currently tells the core that
it is capable of attaching up to WCN36XX_MAX_SCAN_IE_LEN octets, but
doesn't actually pass them to the the hardware.

Note that this patch doesn't fix a bug that was observed. The change is
merely done for the sake of completeness as the hardware supports
appending IEs in scans. Tests show that network scans work fine with
this patch applied.

Some defines were moved around to avoid cyclic include dependencies.

Signed-off-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>