qcom_target: Add wlan-caf to CFI paths

* The default AOSP hardware/qcom/wlan path is listed in
  PRODUCT_CFI_INCLUDE_PATHS since wpa_supplicant is compiled with
  control flow integrity checks. Add the Qualcomm WLAN variant to
  PRODUCT_CFI_INCLUDE_PATHS as well so wpa_supplicant can safely link
  it without exploding.

Change-Id: Id5577846e1e1ea11f8a665d62847c80803e285f7