gpu: imx: fix support for interlaced modes

The support for interlaced video modes seems to be broken; we don't use
anything other than the vtotal/htotal from the timing information to
define the various sync counters.

Freescale patches for interlaced video support contain an alternative
sync counter setup, which we include here.  This setup produces the
hsync and vsync via the normal counter 2 and 3, but moves the display
enable signal from counter 5 to counter 6.  Therefore, we need to
change the display controller setup as well.

The corresponding Freescale patches for this change are:
  iMX6-HDMI-support-interlaced-display-mode.patch
  IPU-fine-tuning-the-interlace-display-timing-for-CEA.patch

This produces a working interlace format output from the IPU.

Tested-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>