net: wireless: Cypress: fix use-after-free in _dhd_pno_get_for_batch

CVE-2017-0430

Found one possible use-after-free in _dhd_pno_get_for_batch().
In case where "pscan_result->cnt_header==0", the kernel try to
free 'pscan_results' and immediately try to dereference it again.

Change-Id: I53504cdc6ca447547b879c52a2468a82ebd73daf