staging: brcm80211: Fix for suspend issue in brcmfmac driver

Currently, there are 2 callbacks registered with OS for getting
notifications when system goes to suspend/resume. Racing between
these 2 callbacks results in random suspend failures. With this fix,
we avoid registering dhd callback for suspend/resume notification
when cfg80211 is used. Relevent functionality in dhd suspend/resume
callback function is moved to cfg80211 suspend/resume functions.

Cc: devel@linuxdriverproject.org
Cc: linux-wireless@vger.kernel.org
Cc: Grant Grundler <grundler@chromium.org>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Reviewed-by: Brett Rudley <brudley@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>