radio-iris: fix memory leak issue for hci dev

On FM closure, free the memory allocated for hci device. Make the
register/unregister call symmetric. Also, do not free the video device on
FM closure as it is allocated in platform driver probe and removed in
remove call.

CRs-Fixed: 981131
Change-Id: Ibc5d287083572ab1686a91cc7b934ae66f749e27
Signed-off-by: Rupesh Tatiya <rtatiya@codeaurora.org>