net: wireless: bcmdhd: Clean scan status if request is empty

Change-Id: I1c00b5a84846faf316305f57a6a74ded2288a6fd
Signed-off-by: Dmitry Shmidt <dimitrysh@google.com>
(cherry picked from commit 06a8b59a9f5dc8bc70df187ce8d22e06f1460073)