Fix intermittent hotplug lost issue because of page flip.

Fix intermittent hotplug lost issue because of page flip.

Since the DRM page flip mechanism keeps updatign the crtc->fb member
with the current fb to be flipped, this gets out-of-sync with the
psb_fb_helper->fb member. In the event of a HDMI hotplug, this mismatch
causes the HDMI hotplug event to be deferred and never handled. Ensure
that we are keeping both the members in sync always during flip.

Signed-off-by: Arun Kannan <arun.kannan@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>