qcacld-3.0: SAP Rx: get sta_id for dhcp packet only

Check for dhcp packet type before processing on packet sta_id.
This reduces per packet mem_copy and mem_cmp instructions for
sap Rx.

Change-Id: I4a2732ff4d9e3fa31aace25cc824f26b0c339b52
CRs-Fixed: 2331420
1 file changed