hammerhead: initial wlan bring up

- Add wlan-related dev notes and services.
- Add p2p_supplicant.conf and wpa_supplicant.conf.
- Add calibration data
- Set wlan configuration on BoardConfig.mk.
- Include broadcom wlan makefile

Change-Id: I3d1f4357db4a34b67a7bf28a297e942ef9e5a6ae
7 files changed