hostapd: Avoid SIGSEGV by NULL check for hw_features

NULL check for iface->hw_features to avoid segmentation fault
at stapolicy_cfg_init().

BUG=b:78523461
TEST=compile hostapd

Change-Id: Ia182cd2725fc22f43a225707a8446fd81a3c1569
Reviewed-on: https://chromium-review.googlesource.com/1046728
Commit-Ready: Dheeraj KM <dheeraj.km@globaledgesoft.com>
Tested-by: Dheeraj KM <dheeraj.km@globaledgesoft.com>
Reviewed-by: Srinivasa duvvuri <sduvvuri@google.com>
Reviewed-by: NARAYANRADDI MASTI <nmasti@google.com>
1 file changed